Line Spacing in LaTeX

\usepackage{setspace}

% In preamble (after \usepackage{setspace}):
\singlespacing     % 1× (LaTeX default)
\onehalfspacing    % 1.5× spacing
\doublespacing     % 2× spacing

% Custom multiplier:
\setstretch{1.25}  % 1.25× spacing

Main body text at normal spacing.

\begin{doublespace}
  This paragraph has double spacing.
\end{doublespace}

\begin{singlespace}
  Block quotes and code listings are often single-spaced
  even in a double-spaced document.
\end{singlespace}

\begin{spacing}{1.3}
  Custom 1.3× spacing for this block.
\end{spacing}

% setspace automatically keeps footnotes single-spaced.
% No extra code needed — just \doublespacing in the preamble.

\usepackage{parskip}
% Automatically sets \parskip and removes \parindent

% Or manually:
\setlength{\parskip}{6pt}
\setlength{\parindent}{0pt}

% Low-level approach (not recommended for full documents):
\renewcommand{\baselinestretch}{1.5}
\normalsize  % must follow to take effect