Those are WP-defined functions/variables. To look at definition, browse the source code.
I don’t really understand the question, by the way 😛
See this Codex page on conditional tags:
http://codex.wordpress.org/Conditional_Tags
If you’re asking how to perform similar conditional testing outside of WP, a somewhat equivalent method would be to use $_GET and verify the query type.
Thread Starter
syni
(@syni)
Okay, I was putting something together on how to call stylesheets by page, and I know how to do it in WordPress, but I was getting ready in case anybody asked how to do it outside of WordPress.