Creating Diagrams with TikZ

\documentclass{article}
\usepackage{tikz}

% Load common libraries
\usetikzlibrary{
    arrows.meta,      % Arrow styles
    positioning,      % Relative positioning
    shapes.geometric, % Additional shapes
    calc,            % Coordinate calculations
    patterns,        % Fill patterns
    decorations.pathmorphing, % Path decorations
    backgrounds,     % Background layers
    fit,            % Fitting nodes
    chains,         % Chain positioning
    shadows         % Drop shadows
}

\begin{document}

% Inline TikZ
\begin{tikzpicture}
    \draw (0,0) -- (2,1);
\end{tikzpicture}

% Centered figure
\begin{figure}[htbp]
    \centering
    \begin{tikzpicture}
        % Drawing commands here
    \end{tikzpicture}
    \caption{TikZ diagram}
\end{figure}

\end{document}

% Basic shapes and lines
\begin{tikzpicture}
    % Grid for reference (remove in final)
    \draw[help lines, gray] (0,0) grid (6,4);
    
    % Lines
    \draw (0,0) -- (2,1);                    % Straight line
    \draw[thick] (3,0) -- (5,1);             % Thick line
    \draw[dashed] (0,2) -- (2,3);            % Dashed line
    \draw[->] (3,2) -- (5,3);                % Arrow
    \draw[<->, red] (0,3.5) -- (2,3.5);      % Double arrow
    
    % Basic shapes
    \draw (1,1) circle (0.5);                % Circle
    \draw[fill=blue!20] (4,1) circle (0.5);  % Filled circle
    \draw (0,0) rectangle (1,0.8);           % Rectangle
    \draw[rounded corners] (3,0) rectangle (4,0.8); % Rounded
    
    % Nodes (shapes with text)
    \node[circle, draw] at (1,3) {A};
    \node[rectangle, draw, fill=green!20] at (4,3) {Box};
\end{tikzpicture}

\begin{tikzpicture}[scale=1.5]
    % Cartesian coordinates
    \draw[->] (-0.5,0) -- (4,0) node[right] {$x$};
    \draw[->] (0,-0.5) -- (0,3) node[above] {$y$};
    
    % Points
    \fill (1,1) circle (2pt) node[below] {$(1,1)$};
    \fill (3,2) circle (2pt) node[right] {$(3,2)$};
    
    % Path with multiple segments
    \draw[thick, blue] (0,0) -- (1,1) -- (2,0.5) -- (3,2);
    
    % Curved path
    \draw[thick, red] (0,2) .. controls (1,3) and (2,1) .. (3,2.5);
    
    % Closed path
    \draw[thick, green, fill=green!20] 
        (0.5,0.5) -- (1.5,0.5) -- (1,1.5) -- cycle;
        
    % Polar coordinates
    \draw[purple] (0,0) -- (45:2) node[midway, above] {$(45:2)$};
    
    % Relative coordinates
    \draw[orange, thick] (2,1) -- ++(1,0.5) -- ++(0.5,-0.5);
\end{tikzpicture}

\begin{tikzpicture}[scale=1.2]
    % Different path operations
    
    % Straight lines with corners
    \draw[blue] (0,0) -| (2,1);  % Horizontal then vertical
    \draw[red] (3,0) |- (5,1);   % Vertical then horizontal
    
    % Bezier curves
    \draw[thick] (0,2) .. controls (1,3) .. (2,2);
    \draw[thick, green] (3,2) .. controls (3.5,3) and (4.5,3) .. (5,2);
    
    % Arcs
    \draw[thick, orange] (1,3) arc (0:90:1);
    \draw[thick, purple] (4,3) arc (180:45:1.5);
    
    % Smooth curves through points
    \draw[thick, brown] plot[smooth] coordinates {
        (0,4) (0.5,4.5) (1,4.2) (1.5,4.8) (2,4.3)
    };
    
    % Cycle back to start
    \draw[thick, cyan, fill=cyan!20] 
        (3,4) -- (4,4.5) -- (5,4) -- (4,3.5) -- cycle;
\end{tikzpicture}

\begin{tikzpicture}[
    every node/.style={font=\sffamily},
    main node/.style={circle, draw, minimum size=1cm}
]
    % Basic nodes
    \node (A) at (0,0) {Simple text};
    \node[draw] (B) at (3,0) {Boxed text};
    \node[circle, draw] (C) at (6,0) {Circle};
    
    % Styled nodes
    \node[main node, fill=blue!20] (D) at (0,2) {D};
    \node[rectangle, draw, rounded corners, fill=red!20] (E) at (3,2) {Rect};
    \node[ellipse, draw, fill=green!20] (F) at (6,2) {Ellipse};
    
    % Node connections
    \draw[->] (A) -- (B);
    \draw[->] (B) -- (C);
    \draw[<->, thick] (D) -- (E);
    \draw[->, dashed] (E) -- (F);
    
    % Labels on edges
    \draw[->] (D) -- (A) node[midway, left] {edge};
    \draw[->] (F) -- (C) node[near start, right] {label};
\end{tikzpicture}

\begin{tikzpicture}[
    node distance=2cm,
    box/.style={rectangle, draw, minimum width=2cm, minimum height=1cm}
]
    % Central node
    \node[box, fill=yellow!30] (center) {Center};
    
    % Relative positioning
    \node[box, above=of center] (top) {Above};
    \node[box, below=of center] (bottom) {Below};
    \node[box, left=of center] (left) {Left};
    \node[box, right=of center] (right) {Right};
    
    % Diagonal positioning
    \node[box, above right=of center] (tr) {Top Right};
    \node[box, below left=of center] (bl) {Bottom Left};
    
    % Custom distances
    \node[box, above=3cm of center] (far) {Far Above};
    \node[box, right=1cm of center] (near) {Near Right};
    
    % Connect all to center
    \foreach \n in {top, bottom, left, right, tr, bl, far, near}
        \draw[->] (center) -- (\n);
\end{tikzpicture}

\begin{tikzpicture}[
    node distance=2cm,
    startstop/.style={rectangle, rounded corners, draw, fill=red!30, minimum width=3cm, minimum height=1cm},
    process/.style={rectangle, draw, fill=blue!30, minimum width=3cm, minimum height=1cm},
    decision/.style={diamond, draw, fill=green!30, minimum width=3cm, minimum height=1cm, aspect=2},
    io/.style={trapezium, trapezium left angle=70, trapezium right angle=110, draw, fill=yellow!30, minimum width=3cm, minimum height=1cm},
    arrow/.style={thick, ->, >=stealth}
]
    % Nodes
    \node[startstop] (start) {Start};
    \node[io, below=of start] (input) {Input data};
    \node[process, below=of input] (process1) {Process data};
    \node[decision, below=of process1] (decision) {Valid?};
    \node[process, below=of decision] (process2) {Generate output};
    \node[startstop, below=of process2] (stop) {End};
    
    % Alternative path
    \node[process, right=3cm of decision] (error) {Handle error};
    
    % Connections
    \draw[arrow] (start) -- (input);
    \draw[arrow] (input) -- (process1);
    \draw[arrow] (process1) -- (decision);
    \draw[arrow] (decision) -- node[left] {Yes} (process2);
    \draw[arrow] (decision) -- node[above] {No} (error);
    \draw[arrow] (error) |- (input);
    \draw[arrow] (process2) -- (stop);
\end{tikzpicture}

\begin{tikzpicture}[
    node distance=1.5cm and 2cm,
    box/.style={rectangle, draw, fill=#1, minimum width=2.5cm, minimum height=0.8cm, font=\small},
    decision/.style={diamond, draw, fill=orange!30, aspect=1.5, font=\small},
    cloud/.style={cloud, draw, fill=gray!20, minimum width=2cm, minimum height=1cm},
    database/.style={cylinder, draw, fill=purple!30, minimum width=2cm, minimum height=1cm, shape border rotate=90},
    arr/.style={->, >=latex, thick}
]
    % System architecture flowchart
    \node[cloud] (user) {User};
    \node[box=blue!30, below=of user] (ui) {UI Layer};
    \node[box=green!30, below=of ui] (api) {API Gateway};
    \node[decision, below=of api] (auth) {Authenticated?};
    \node[box=yellow!30, below left=of auth] (login) {Login Service};
    \node[box=cyan!30, below right=of auth] (service) {Business Logic};
    \node[database, below=of service] (db) {Database};
    \node[box=red!30, right=of service] (cache) {Cache};
    
    % Connections with labels
    \draw[arr] (user) -- (ui);
    \draw[arr] (ui) -- (api) node[midway, right] {HTTP};
    \draw[arr] (api) -- (auth);
    \draw[arr] (auth) -- node[left] {No} (login);
    \draw[arr] (auth) -- node[right] {Yes} (service);
    \draw[arr] (login) -| (api);
    \draw[arr] (service) -- (db) node[midway, right] {Query};
    \draw[arr, <->] (service) -- (cache) node[midway, above] {Read/Write};
    \draw[arr] (db) -| (cache) node[near start, left] {Update};
\end{tikzpicture}

\begin{tikzpicture}[
    >=stealth,
    node distance=3cm,
    state/.style={circle, draw, minimum size=1.5cm, font=\small},
    initial/.style={state, fill=green!30},
    final/.style={state, double, fill=red!30},
    transition/.style={->, thick}
]
    % States
    \node[initial] (idle) {Idle};
    \node[state, right=of idle] (loading) {Loading};
    \node[state, right=of loading] (active) {Active};
    \node[state, below=of active] (error) {Error};
    \node[final, below=of idle] (terminated) {Done};
    
    % Transitions
    \draw[transition] (idle) -- node[above] {start} (loading);
    \draw[transition] (loading) -- node[above] {success} (active);
    \draw[transition] (loading) -- node[right] {fail} (error);
    \draw[transition] (active) -- node[right] {complete} (terminated);
    \draw[transition] (error) -- node[below] {retry} (loading);
    \draw[transition] (error) -- node[left] {abort} (terminated);
    \draw[transition, bend left=30] (active) to node[above] {reset} (idle);
    
    % Self loop
    \draw[transition] (active) to[loop above] node {update} (active);
\end{tikzpicture}

\begin{tikzpicture}[
    shorten >=1pt,
    node distance=2.5cm,
    on grid,
    auto,
    state/.style={circle, draw, minimum size=1.2cm},
    accepting/.style={state, double}
]
    % Finite automaton
    \node[state, initial] (q0) {$q_0$};
    \node[state] (q1) [right=of q0] {$q_1$};
    \node[state] (q2) [right=of q1] {$q_2$};
    \node[accepting] (q3) [right=of q2] {$q_3$};
    
    % Transitions
    \path[->]
        (q0) edge node {0} (q1)
        (q0) edge[loop above] node {1} (q0)
        (q1) edge node {1} (q2)
        (q1) edge[bend left] node {0} (q0)
        (q2) edge node {0} (q3)
        (q2) edge[bend left] node[below] {1} (q1)
        (q3) edge[loop above] node {0,1} (q3);
        
    % Label
    \node[below=2cm of q1, text width=6cm, align=center] {
        Finite automaton accepting strings with exactly three 0s
    };
\end{tikzpicture}

\begin{tikzpicture}[
    node distance=2cm,
    vertex/.style={circle, draw, fill=blue!20, minimum size=8mm},
    edge/.style={thick}
]
    % Vertices
    \node[vertex] (A) {A};
    \node[vertex, right=of A] (B) {B};
    \node[vertex, below right=of A] (C) {C};
    \node[vertex, below left=of A] (D) {D};
    \node[vertex, below=of C] (E) {E};
    
    % Edges
    \draw[edge] (A) -- (B);
    \draw[edge] (A) -- (C);
    \draw[edge] (A) -- (D);
    \draw[edge] (B) -- (C);
    \draw[edge] (C) -- (D);
    \draw[edge] (C) -- (E);
    \draw[edge] (D) -- (E);
    
    % Edge labels
    \draw[edge] (B) -- node[above right] {5} (E);
\end{tikzpicture}

\begin{tikzpicture}[
    scale=1.5,
    vertex/.style={circle, draw, fill=orange!30, minimum size=10mm, font=\footnotesize},
    edge/.style={->, >=stealth, thick},
    weight/.style={midway, font=\scriptsize, fill=white, inner sep=1pt}
]
    % Weighted directed graph
    \node[vertex] (1) at (0,2) {1};
    \node[vertex] (2) at (2,3) {2};
    \node[vertex] (3) at (4,2) {3};
    \node[vertex] (4) at (3,0) {4};
    \node[vertex] (5) at (1,0) {5};
    
    % Weighted edges
    \draw[edge] (1) -- node[weight] {3} (2);
    \draw[edge] (2) -- node[weight] {1} (3);
    \draw[edge] (3) -- node[weight] {4} (4);
    \draw[edge] (4) -- node[weight] {2} (5);
    \draw[edge] (5) -- node[weight] {6} (1);
    \draw[edge] (1) -- node[weight] {5} (3);
    \draw[edge] (2) -- node[weight] {2} (4);
    
    % Self loop
    \draw[edge] (3) to[loop right] node[weight] {1} (3);
\end{tikzpicture}

\begin{tikzpicture}[
    level distance=1.5cm,
    level 1/.style={sibling distance=4cm},
    level 2/.style={sibling distance=2cm},
    level 3/.style={sibling distance=1cm},
    treenode/.style={circle, draw, fill=green!30, minimum size=8mm},
    edge from parent/.style={draw, ->, >=stealth}
]
    % Binary tree
    \node[treenode] {8}
        child {
            node[treenode] {3}
            child {
                node[treenode] {1}
            }
            child {
                node[treenode] {6}
                child {
                    node[treenode] {4}
                }
                child {
                    node[treenode] {7}
                }
            }
        }
        child {
            node[treenode] {10}
            child[missing] {}
            child {
                node[treenode] {14}
                child {
                    node[treenode] {13}
                }
                child[missing] {}
            }
        };
\end{tikzpicture}

\begin{tikzpicture}[
    grow=down,
    level 1/.style={sibling distance=5cm},
    level 2/.style={sibling distance=2.5cm},
    level 3/.style={sibling distance=1.5cm},
    edge from parent/.style={draw, thick},
    nodeStyle/.style={rectangle, draw, fill=cyan!20, minimum width=2cm, minimum height=0.8cm, font=\small},
    leafStyle/.style={nodeStyle, fill=yellow!30}
]
    % Organizational chart style tree
    \node[nodeStyle] {CEO}
        child {
            node[nodeStyle] {CTO}
            child {
                node[nodeStyle] {Dev Team}
                child { node[leafStyle] {Frontend} }
                child { node[leafStyle] {Backend} }
            }
            child {
                node[nodeStyle] {DevOps}
                child { node[leafStyle] {Cloud} }
                child { node[leafStyle] {Security} }
            }
        }
        child {
            node[nodeStyle] {CFO}
            child { node[leafStyle] {Accounting} }
            child { node[leafStyle] {Finance} }
        }
        child {
            node[nodeStyle] {CMO}
            child { node[leafStyle] {Marketing} }
            child { node[leafStyle] {Sales} }
        };
        
    % Alternative: horizontal tree
    \begin{scope}[xshift=10cm]
        \tikzset{
            grow=right,
            level 1/.style={sibling distance=2cm, level distance=2.5cm},
            level 2/.style={sibling distance=1cm, level distance=2.5cm}
        }
        \node[nodeStyle] {Root}
            child { 
                node[nodeStyle] {A}
                child { node[leafStyle] {A1} }
                child { node[leafStyle] {A2} }
            }
            child {
                node[nodeStyle] {B}
                child { node[leafStyle] {B1} }
            };
    \end{scope}
\end{tikzpicture}

\begin{tikzpicture}[scale=1.5]
    % Axes
    \draw[->] (-0.5,0) -- (4,0) node[right] {$x$};
    \draw[->] (0,-0.5) -- (0,3) node[above] {$y$};
    
    % Grid
    \draw[gray, very thin] (0,0) grid (3.5,2.5);
    
    % Function plots
    \draw[blue, thick, domain=0:3.5, samples=100] 
        plot (\x, {0.5*\x*\x - \x + 1});
    \draw[red, thick, domain=0:3.5, samples=100] 
        plot (\x, {sin(\x r) + 1});
    \draw[green, thick, domain=0.1:3.5, samples=100] 
        plot (\x, {ln(\x) + 1});
        
    % Labels
    \node[blue] at (3,2.2) {$f(x) = \frac{1}{2}x^2 - x + 1$};
    \node[red] at (2,0.3) {$g(x) = \sin(x) + 1$};
    \node[green] at (3.2,1.3) {$h(x) = \ln(x) + 1$};
    
    % Points of interest
    \fill[blue] (2,1) circle (2pt) node[above right] {$(2,1)$};
\end{tikzpicture}

\begin{tikzpicture}[scale=2]
    % Triangle with labels
    \coordinate[label=left:$A$] (A) at (0,0);
    \coordinate[label=right:$B$] (B) at (3,0);
    \coordinate[label=above:$C$] (C) at (1.5,2);
    
    % Draw triangle
    \draw[thick] (A) -- (B) -- (C) -- cycle;
    
    % Angles
    \draw[fill=red!20] (A) -- (0.5,0) arc (0:53.13:0.5) -- cycle;
    \draw[fill=blue!20] (B) -- (2.5,0) arc (180:126.87:0.5) -- cycle;
    \draw[fill=green!20] (C) -- (1.5,1.5) arc (270:270-73.74:0.5) -- cycle;
    
    % Angle labels
    \node at (0.7,0.2) {$\alpha$};
    \node at (2.3,0.2) {$\beta$};
    \node at (1.5,1.6) {$\gamma$};
    
    % Side labels
    \node[below] at (1.5,0) {$c$};
    \node[above right] at (2.25,1) {$a$};
    \node[above left] at (0.75,1) {$b$};
    
    % Height
    \draw[dashed] (C) -- (1.5,0) node[midway, right] {$h$};
    \fill (1.5,0) circle (1pt);
\end{tikzpicture}

\begin{tikzpicture}[
    force/.style={->, thick, blue},
    mass/.style={rectangle, draw, fill=gray!30, minimum width=1.5cm, minimum height=1.5cm}
]
    % Free body diagram
    \node[mass] (m) {$m$};
    
    % Forces
    \draw[force] (m.north) -- ++(0,2) node[above] {$N$};
    \draw[force] (m.south) -- ++(0,-2) node[below] {$mg$};
    \draw[force] (m.east) -- ++(1.5,0) node[right] {$F$};
    \draw[force] (m.west) -- ++(-1,0) node[left] {$f$};
    
    % Surface
    \draw[thick] (-3,-0.75) -- (3,-0.75);
    \foreach \x in {-3,-2.5,...,3} {
        \draw (\x,-0.75) -- (\x-0.25,-1);
    }
    
    % Angle for inclined plane
    \begin{scope}[xshift=6cm]
        \draw[thick] (0,0) -- (4,0) -- (4,2) -- cycle;
        \node[mass, rotate=26.57] at (2.5,1.25) {$m$};
        \draw[force] (2.5,1.25) -- ++(0,-2) node[below] {$mg$};
        \draw[force, rotate=26.57] (2.5,1.25) -- ++(0,1.5) node[above] {$N$};
        \node at (0.5,0.15) {$\theta$};
    \end{scope}
\end{tikzpicture}

\begin{tikzpicture}[circuit ee IEC]
    % Simple circuit
    \draw (0,0) to[battery] (0,3)
          to[ammeter] (3,3)
          to[resistor={info=$R_1$}] (3,1.5)
          to[resistor={info=$R_2$}] (3,0)
          -- (0,0);
          
    % Parallel circuit
    \begin{scope}[xshift=5cm]
        \draw (0,0) to[voltage source] (0,3) -- (1,3)
              to[resistor={info=$R_1$}] (3,3) -- (4,3)
              -- (4,0) -- (0,0);
        \draw (1,3) -- (1,2)
              to[resistor={info=$R_2$}] (3,2) -- (3,3);
        \draw (1,2) -- (1,1)
              to[capacitor={info=$C$}] (3,1) -- (3,2);
    \end{scope}
\end{tikzpicture}

\begin{tikzpicture}
    % Grid of nodes using foreach
    \foreach \x in {0,1,2,3,4} {
        \foreach \y in {0,1,2,3} {
            \node[circle, draw, fill=blue!\x0!green!\y0] 
                at (\x,\y) {\tiny \x,\y};
        }
    }
    
    % Radial pattern
    \begin{scope}[xshift=7cm, yshift=2cm]
        \foreach \angle in {0,30,...,330} {
            \draw[thick, color=red!\angle!blue] 
                (0,0) -- (\angle:2);
            \fill[color=red!\angle!blue] 
                (\angle:2) circle (2pt);
        }
    \end{scope}
    
    % Connected graph
    \begin{scope}[yshift=-5cm]
        \foreach \i in {1,...,6} {
            \node[circle, draw, fill=orange!30] 
                (n\i) at ({360/6 * (\i-1)}:2) {\i};
        }
        \foreach \i in {1,...,6} {
            \foreach \j in {\i,...,6} {
                \draw[gray] (n\i) -- (n\j);
            }
        }
    \end{scope}
\end{tikzpicture}

\begin{tikzpicture}
    % Using calculations
    \coordinate (A) at (0,0);
    \coordinate (B) at (4,0);
    \coordinate (C) at (2,3);
    
    % Midpoints
    \coordinate (MAB) at ($(A)!0.5!(B)$);
    \coordinate (MBC) at ($(B)!0.5!(C)$);
    \coordinate (MCA) at ($(C)!0.5!(A)$);
    
    % Draw triangle and medians
    \draw[thick] (A) -- (B) -- (C) -- cycle;
    \draw[dashed, red] (A) -- (MBC);
    \draw[dashed, red] (B) -- (MCA);
    \draw[dashed, red] (C) -- (MAB);
    
    % Centroid (intersection of medians)
    \coordinate (G) at (barycentric cs:A=1,B=1,C=1);
    \fill[red] (G) circle (2pt) node[below] {$G$};
    
    % Perpendicular lines
    \draw[blue, thick] (A) -- ($(B)!(A)!(C)$);
    
    % Circle through three points
    \node[draw, circle through=(A)(B)(C)] {};
\end{tikzpicture}

\begin{tikzpicture}[
    % Define custom styles
    my node/.style={
        circle, 
        draw=#1, 
        fill=#1!20, 
        minimum size=1cm,
        font=\bfseries
    },
    my edge/.style={
        thick,
        ->,
        >=stealth,
        #1
    },
    important/.style={
        my node=red,
        drop shadow
    },
    normal/.style={
        my node=blue
    }
]
    % Use custom styles
    \node[important] (A) at (0,0) {A};
    \node[normal] (B) at (3,0) {B};
    \node[normal] (C) at (3,3) {C};
    \node[important] (D) at (0,3) {D};
    
    % Styled edges
    \draw[my edge={red, dashed}] (A) -- (B);
    \draw[my edge={blue}] (B) -- (C);
    \draw[my edge={green, bend left}] (C) -- (D);
    \draw[my edge={orange, bend right}] (D) -- (A);
    
    % Scope with different settings
    \begin{scope}[xshift=6cm, scale=0.8, opacity=0.7]
        \node[my node=purple] (E) at (0,0) {E};
        \node[my node=cyan] (F) at (2,2) {F};
        \draw[my edge={thick}] (E) -- (F);
    \end{scope}
\end{tikzpicture}

\begin{tikzpicture}
    % Background layer
    \begin{pgfonlayer}{background}
        \fill[yellow!20] (-1,-1) rectangle (5,4);
        \fill[blue!20] (1,0.5) circle (2);
    \end{pgfonlayer}
    
    % Main layer
    \draw[thick] (0,0) grid (4,3);
    \node[circle, draw, fill=white] at (2,1.5) {Main};
    
    % Foreground layer
    \begin{pgfonlayer}{foreground}
        \node[rectangle, draw, fill=red!70, opacity=0.8] at (3,2) {Front};
    \end{pgfonlayer}
\end{tikzpicture}

\begin{tikzpicture}[
    decoration={
        snake,
        amplitude=.5mm,
        segment length=3mm
    }
]
    % Different decorations
    \draw[decorate, thick] (0,0) -- (3,0) node[right] {snake};
    
    \draw[
        decoration={coil, segment length=4mm},
        decorate, thick
    ] (0,1) -- (3,1) node[right] {coil};
    
    \draw[
        decoration={zigzag, segment length=4mm},
        decorate, thick
    ] (0,2) -- (3,2) node[right] {zigzag};
    
    \draw[
        decoration={random steps, segment length=3mm},
        decorate, thick
    ] (0,3) -- (3,3) node[right] {random};
    
    % Text along path
    \draw[
        decoration={
            text along path,
            text={This text follows the curve!}
        },
        decorate
    ] (5,0) .. controls (6,2) and (7,2) .. (8,0);
    
    % Arrow decorations
    \draw[
        thick,
        decoration={
            markings,
            mark=at position 0.25 with {\arrow{>}},
            mark=at position 0.5 with {\arrow{>}},
            mark=at position 0.75 with {\arrow{>}}
        },
        postaction={decorate}
    ] (5,3) circle (1);
\end{tikzpicture}

\begin{tikzpicture}
    % Pattern fills
    \fill[pattern=horizontal lines] (0,0) rectangle (2,1);
    \fill[pattern=vertical lines] (2.5,0) rectangle (4.5,1);
    \fill[pattern=north east lines] (5,0) rectangle (7,1);
    \fill[pattern=grid] (7.5,0) rectangle (9.5,1);
    
    % Custom patterns
    \fill[pattern=dots] (0,2) rectangle (2,3);
    \fill[pattern=crosshatch] (2.5,2) rectangle (4.5,3);
    \fill[pattern=fivepointed stars] (5,2) rectangle (7,3);
    \fill[pattern=bricks] (7.5,2) rectangle (9.5,3);
    
    % Combining patterns and colors
    \fill[pattern=north west lines, pattern color=blue] 
        (0,4) rectangle (2,5);
    \fill[pattern=checkerboard, pattern color=red] 
        (2.5,4) rectangle (4.5,5);
    
    % Gradient fills
    \shade[left color=red, right color=blue] (5,4) rectangle (7,5);
    \shade[inner color=yellow, outer color=orange] (7.5,4) circle (0.5);
\end{tikzpicture}

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning, shapes.geometric, shadows, backgrounds}

\begin{document}

\begin{tikzpicture}[
    node distance=2cm,
    server/.style={
        rectangle, draw, fill=blue!20,
        minimum width=2cm, minimum height=1.5cm,
        drop shadow, font=\small
    },
    client/.style={
        rectangle, draw, fill=green!20,
        minimum width=1.5cm, minimum height=1cm,
        drop shadow, font=\small
    },
    database/.style={
        cylinder, draw, fill=orange!20,
        minimum width=2cm, minimum height=1.5cm,
        shape border rotate=90,
        drop shadow, font=\small
    },
    cloud/.style={
        cloud, draw, fill=gray!20,
        minimum width=3cm, minimum height=2cm,
        drop shadow, font=\small
    },
    connection/.style={thick, ->, >=stealth},
    label/.style={font=\footnotesize, fill=white, inner sep=2pt}
]
    % Core components
    \node[cloud] (internet) {Internet};
    \node[server, below=3cm of internet] (loadbalancer) {Load Balancer};
    
    % Web servers
    \node[server, below left=2cm and 1cm of loadbalancer] (web1) {Web Server 1};
    \node[server, below right=2cm and 1cm of loadbalancer] (web2) {Web Server 2};
    
    % Application servers
    \node[server, below=of web1] (app1) {App Server 1};
    \node[server, below=of web2] (app2) {App Server 2};
    
    % Databases
    \node[database, below right=2cm and 0cm of app1] (db1) {Primary DB};
    \node[database, right=1cm of db1] (db2) {Replica DB};
    
    % Clients
    \node[client, left=3cm of internet] (client1) {Client 1};
    \node[client, above left=1cm and 2cm of internet] (client2) {Client 2};
    \node[client, above right=1cm and 2cm of internet] (client3) {Client 3};
    
    % Connections
    \draw[connection] (client1) -- (internet);
    \draw[connection] (client2) -- (internet);
    \draw[connection] (client3) -- (internet);
    
    \draw[connection, <->] (internet) -- node[label] {HTTPS} (loadbalancer);
    
    \draw[connection] (loadbalancer) -- (web1);
    \draw[connection] (loadbalancer) -- (web2);
    
    \draw[connection] (web1) -- (app1);
    \draw[connection] (web2) -- (app2);
    
    \draw[connection] (app1) -- (db1);
    \draw[connection] (app2) -- (db1);
    \draw[connection, <->] (db1) -- node[label] {Sync} (db2);
    
    % Background regions
    \begin{pgfonlayer}{background}
        \fill[yellow!20, rounded corners] 
            ([shift={(-0.5,0.5)}]loadbalancer.north west) 
            rectangle 
            ([shift={(0.5,-0.5)}]db2.south east);
        \node[above] at (loadbalancer.north) {Data Center};
    \end{pgfonlayer}
\end{tikzpicture}

\end{document}

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta, positioning, shapes, decorations.pathmorphing}

\begin{document}

\begin{tikzpicture}[
    >=latex,
    node distance=2.5cm,
    process/.style={
        rectangle, draw, fill=blue!30,
        minimum width=3cm, minimum height=1cm,
        rounded corners, font=\small\sffamily
    },
    data/.style={
        trapezium, draw, fill=green!30,
        trapezium left angle=70,
        trapezium right angle=110,
        minimum width=2.5cm, minimum height=0.8cm,
        font=\small\sffamily
    },
    storage/.style={
        rectangle, draw, fill=orange!30,
        minimum width=2.5cm, minimum height=0.8cm,
        path picture={
            \draw ([xshift=0.1cm]path picture bounding box.north west) 
                -- ([xshift=-0.1cm]path picture bounding box.north east);
        },
        font=\small\sffamily
    },
    flow/.style={thick, ->, >=stealth},
    label/.style={font=\footnotesize, above, sloped}
]
    % Input layer
    \node[data] (input) {Raw Data};
    
    % Processing pipeline
    \node[process, below=of input] (validate) {Validate};
    \node[process, below=of validate] (transform) {Transform};
    \node[process, below=of transform] (analyze) {Analyze};
    
    % Storage
    \node[storage, right=3cm of validate] (raw) {Raw Storage};
    \node[storage, right=3cm of transform] (processed) {Processed DB};
    \node[storage, right=3cm of analyze] (results) {Results Cache};
    
    % Output
    \node[data, below=of analyze] (output) {Reports};
    \node[process, right=of output] (visualize) {Visualize};
    \node[data, right=of visualize] (dashboard) {Dashboard};
    
    % Main flow
    \draw[flow] (input) -- node[label] {Stream} (validate);
    \draw[flow] (validate) -- node[label] {Valid} (transform);
    \draw[flow] (transform) -- node[label] {Clean} (analyze);
    \draw[flow] (analyze) -- node[label] {Insights} (output);
    
    % Storage connections
    \draw[flow, dashed] (validate) -- node[label] {Archive} (raw);
    \draw[flow, dashed] (transform) -- node[label] {Store} (processed);
    \draw[flow, dashed] (analyze) -- node[label] {Cache} (results);
    
    % Visualization flow
    \draw[flow] (output) -- (visualize);
    \draw[flow] (visualize) -- (dashboard);
    \draw[flow, bend right] (results) to node[label, below] {Query} (visualize);
    
    % Error handling
    \node[process, left=2cm of transform, fill=red!30] (error) {Error Handler};
    \draw[flow, red, bend right] (validate) to node[label, below] {Invalid} (error);
    \draw[flow, red, bend right] (transform) to node[label, below] {Failed} (error);
    \draw[flow, red] (error) |- (input);
    
    % Decorations
    \node[above=0.5cm of input, font=\large\bfseries] {Data Processing Pipeline};
    
    % Legend
    \begin{scope}[xshift=8cm, yshift=-3cm]
        \node[process, minimum width=2cm] (l1) at (0,0) {Process};
        \node[data, minimum width=2cm] (l2) at (0,-1) {Data};
        \node[storage, minimum width=2cm] (l3) at (0,-2) {Storage};
        \draw[flow] (3,0) -- node[above] {Flow} (4.5,0);
        \draw[flow, dashed] (3,-1) -- node[above] {Store} (4.5,-1);
        \node[above=0.3cm of l1, font=\bfseries] {Legend};
    \end{scope}
\end{tikzpicture}

\end{document}