How to make a title of two or more lines?

Question

My document has a long title, so I want the title spans two lines.

I've use this:

\title{my title that must be in two or more lines}

but it not works. How can get it?

Answer 1

Use the double backslash:

\documentclass{article}
\begin{document}
\title{First line of title \\
Second line of title}\maketitle
\end{document}

Answer 2

Use the line break operator \\.