How do threads get bumped if there are no new posts?

[dr_skier]

It says new post, then it's the same one as the old one???

 

[SoKlueles]

if its a poll, and someone votes, it gets bumped

 

[ryan04]

bump

 

[immortalis]

does editing a post bump the thread?

 

[Cutiebaby]

its a poll

 

[Gymgurl]

wtf bbq