Double Spacing in LaTex

source: http://albertskblog.blogspot.com/2007/11/to-doublespace-latex-document-you.html

To doublespace a LaTeX document, you should include the line

\usepackage{setspace}

after your \documentclass line.

Before your \begin{document} command,

\doublespacing

will make the text of the whole document doublespaced.  Footnotes,
figures, and tables will still be singlespaced, however. For one-and-a-half
spacing, instead use the command

\onehalfspacing

In order to make a part of the text of your document singlespaced, you can
put:

\begin{singlespace}

at the beginning of the text you want singlespaced, and

\end{singlespace}

at the end.

You can also set the spacing to be something other than doublespaced; for
example, if you wanted to have one-and-a-quarter spacing between lines,
use the line

\setstretch{1.25}

before your \begin{document} command, and after the
\usepackage{setspace} line.