In traditional websites, I like and, in a variety of different ways, frequently use server side includes. I'm currently in the process of converting one of these sites to a WordPress site and I'm now looking for a way to accomplish the same thing(s) within the WordPress system. It's very likely that what I'm trying to accomplich is already possible using standard WordPress features (or perhaps a plug-in may exist); I'm just not sure what terminolgy is used. From what I've seen; includes, snippets, chunks etc have different meaning in the context of WordPress.
If I had a little hunk of info, a piece of code, perhaps a sub-navigation menu, for example, that I wanted to include into several certain pages (not the template) how would I do this?
A related question -to accomplish the same thing- can the content of a "page" appear in another "page"?