How do I escape ampersands in XML so they are rendered as entities in HTML?

Question

I have some XML text that I wish to render in an HTML page. This text contains an ampersand, which I want to render in its entity representation: &.

Answer 1

I have tried &, but it didn't work. Based on Wim ten Brink's answer I tried &amp and it worked.

One of my fellow developers suggested me to use & and that worked regardless of how many times it may be rendered.