LaTeX Paragraph Spacing: \parskip, \parindent, \vspace, and line spacing

\documentclass{article}
\begin{document}

This is the first paragraph. It demonstrates LaTeX's default 
formatting with first-line indentation and no extra spacing 
between paragraphs.

This is the second paragraph. Notice how it starts with an 
indent but has no extra vertical space separating it from 
the previous paragraph.

\end{document}

\documentclass{article}

% Add space between paragraphs
\setlength{\parskip}{1em}

% Remove first-line indent
\setlength{\parindent}{0pt}

\begin{document}

This paragraph has no indentation and is followed by extra space.

This paragraph also has no indentation. The space between 
paragraphs makes the document structure clearer.

% Temporarily change spacing
{\setlength{\parskip}{2em}
These paragraphs have even more space between them.

See how the larger gap creates stronger visual separation.
}

Back to normal spacing here.

\end{document}

\documentclass{article}
\usepackage{setspace}
\begin{document}

% Single spacing (default)
\singlespacing
This text uses single spacing, which is the LaTeX default.

% One and a half spacing
\onehalfspacing
This text uses one-and-a-half spacing, providing more space 
between lines for better readability.

% Double spacing
\doublespacing
This text uses double spacing, often required for academic 
manuscripts and drafts.

% Custom spacing
\setstretch{1.25}
This text uses custom 1.25 line spacing.

% Return to single
\singlespacing

\end{document}

\documentclass{article}
\usepackage{setspace}
\begin{document}

Normal spacing paragraph here.

\begin{doublespace}
This paragraph uses double spacing. It's useful for quotes 
or sections that need emphasis through spacing.
\end{doublespace}

Back to normal spacing.

% Inline spacing change
{\onehalfspacing
This paragraph temporarily uses 1.5 spacing without affecting 
the rest of the document.
}

\end{document}

\documentclass{article}
\begin{document}

First paragraph.

\vspace{1cm}
This paragraph has 1cm of extra space above it.

\vspace{10pt}
This has 10 points of space above.

\bigskip
The bigskip command adds a large vertical space.

\medskip
The medskip command adds medium vertical space.

\smallskip
The smallskip command adds small vertical space.

% Negative space (move up)
\vspace{-5mm}
This paragraph is moved up by 5mm.

\end{document}

% Fixed space
\vspace{2cm}

% Flexible space (can shrink/stretch)
\vspace{2cm plus 1cm minus 0.5cm}

% Fill remaining space
\vfill

% Multiple fills for proportional spacing
Text at top
\vfill
Text in middle (1/3 down)
\vfill
\vfill
Text at bottom

\documentclass{article}
\begin{document}

% Default indented paragraph
This paragraph has the default indentation.

\noindent
This paragraph has no indentation because of the noindent command.

\indent
This paragraph is indented even if global indentation is turned off.

% Change indent size
\setlength{\parindent}{2cm}
This paragraph has a 2cm indent.

% Remove all indentation
\setlength{\parindent}{0pt}
Now all paragraphs have no indentation by default.

\end{document}

\documentclass{article}
\begin{document}

% Simple hanging indent
\hangindent=2cm
\hangafter=1
This paragraph has a hanging indent. The first line starts at the 
left margin, but all subsequent lines are indented by 2cm. This is 
useful for bibliographies and lists.

% Negative hanging indent
\hangindent=-2cm
\hangafter=1
This paragraph has a reverse hanging indent. The first line is 
indented to the right, while subsequent lines extend to the left 
margin.

% Multiple line hanging
\hangindent=1.5cm
\hangafter=2
This paragraph's hanging indent starts after the second line. 
The first two lines are normal, then all following lines are 
indented. This creates an interesting visual effect.

\end{document}

\documentclass{article}
\begin{document}

Regular paragraph before the quote.

\begin{quote}
This is a short quote. It's indented from both margins and 
has no paragraph indentation. Perfect for short excerpts.
\end{quote}

\begin{quotation}
This is a longer quotation environment. Unlike the quote 
environment, it indents the first line of each paragraph.

This is the second paragraph in the quotation, showing 
the first-line indentation.
\end{quotation}

Regular text continues here.

\end{document}

\documentclass{article}

% Define custom environment
\newenvironment{widespace}
  {\par\vspace{1em}\begin{minipage}{\textwidth}\setstretch{1.5}}
  {\end{minipage}\vspace{1em}\par}

\begin{document}

Normal spacing paragraph.

\begin{widespace}
This custom environment adds vertical space before and after, 
plus increases line spacing. It's useful for important passages 
that need visual emphasis.
\end{widespace}

Back to normal spacing.

\end{document}

\documentclass{article}
\usepackage{enumitem}
\begin{document}

% Compact list
\begin{itemize}[noitemsep,topsep=0pt]
\item First item
\item Second item
\item Third item
\end{itemize}

% Wide spacing
\begin{enumerate}[itemsep=1em,topsep=1em]
\item First item with extra space
\item Second item with extra space
\item Third item with extra space
\end{enumerate}

% Custom spacing
\begin{itemize}[
  topsep=5pt,      % Space before list
  partopsep=0pt,   % Space before list if new paragraph
  itemsep=10pt,    % Space between items
  parsep=5pt,      % Space between paragraphs within item
  leftmargin=2cm   % Indent from left
]
\item First customized item
\item Second customized item
\end{itemize}

\end{document}

\documentclass{article}
\usepackage[
  top=2.5cm,
  bottom=2.5cm,
  left=3cm,
  right=2cm,
  headheight=15pt
]{geometry}

% Or use individual commands
% \setlength{\topmargin}{0pt}
% \setlength{\textheight}{9in}
% \setlength{\textwidth}{6.5in}
% \setlength{\oddsidemargin}{0pt}
% \setlength{\evensidemargin}{0pt}

\begin{document}
Content with custom margins...
\end{document}

\documentclass{article}
\usepackage{titlesec}

% Customize section spacing
\titlespacing{\section}
  {0pt}      % Left indent
  {12pt}     % Space before
  {6pt}      % Space after

\titlespacing{\subsection}
  {0pt}{8pt}{4pt}

\begin{document}

\section{First Section}
Text after section heading.

\subsection{Subsection}
Text after subsection.

\end{document}

\documentclass{article}
\begin{document}

% Normal baseline skip
Normal text with default spacing between lines.

% Increase baseline skip
{\setlength{\baselineskip}{20pt}
This text has increased baseline skip, creating more space 
between lines without changing the font size.}

% Proportional baseline skip
{\setlength{\baselineskip}{1.5\baselineskip}
This uses proportional spacing based on the current value.}

\end{document}

% Stretchable space
\hspace{1cm plus 2cm minus 0.5cm}

% Paragraph skip with flexibility
\setlength{\parskip}{6pt plus 2pt minus 1pt}

% Flexible vertical space
\vspace{1cm plus 0.5cm minus 0.2cm}

% Fill space examples
Text\hfill Text  % Horizontal fill
\vfill          % Vertical fill

% Unwanted page breaks
\begin{samepage}
Keep this content together on one page.
\end{samepage}

% Orphan/widow control
\widowpenalty=10000
\clubpenalty=10000

% Prevent spacing at page top
\raggedbottom  % Don't stretch vertical space

% Fix spacing after floats
\clearpage     % Force new page after floats