[Tex/LaTex] Using multiple system fonts

Question

I'd like to use 3-4 different specific system fonts (e.g., Georgia, HelveticaNeui Light, and Lucida Sans) with certain font sizes for different sections of a page. How would I do this?

Edit: Thanks for the responses. I saw the fontspec package but the examples I found defined in the preamble \setmainfont{}, \setsansfont{}, etc. I couldn't figure out how to define a fontfamily and then reference it for a particular section. Here's an example:

\documentclass[12pt]{article}

\usepackage{fontspec}

\begin{document}

\section{Georgia}%here define font

This text shows in Georgia.

\section{Lucida Sans}%

This text shows in Lucida Sans

\section{HelveticaNeue Light}%here define font

This text shows in Helvetica Neue Light

\end{document}

Answer 1

If you just want chunks of text to be a different font you can simply set up environments for them using whatever semantics makes sense for your document. The main thing to remember is that you should use \newfontfamily to define a font switching command for each font rather than using the \fontspec command directly. For example:

% Compile with XeLaTeX or LuaLaTeX
\documentclass[12pt]{article}
\usepackage{fontspec}
\defaultfontfeatures{Ligatures=TeX}

\newfontfamily\calibrifont{Calibri}
\newfontfamily\cambriafont{Cambria}
\newfontfamily\georgiafont{Georgia}

\newenvironment{calibri}{\calibrifont}{\par}
\newenvironment{cambria}{\cambriafont}{\par}
\newenvironment{georgia}{\georgiafont}{\par}

\begin{document}
\begin{calibri}
This text is in Calibri
\end{calibri}
\begin{cambria}
This text is in Cambria
\end{cambria}
\begin{georgia}
This text is in Georgia
\end{georgia}
\end{document}