Why?

Why do some pposts or topics get locked?
and what does sticky mean?

Sticky means it stays at the top of the page

They get locked if the topic has gone off subject, has got people being violent in it, or has simply got too many posts in it. A sticky is when a post is made to stay at the top of the forum the whole time, so it is always obviously seen.
They are used mainly for rules, and topics that often come up.

Oh ok! that makes sence. thanks for the help!

I think posts can also b locked if the question someone wanted has been answered.