While on meme, there are various clicky things I see all the time but half of them mystify me. I figured out EXPAND (and COLLAPSE) and REPLY TO THIS, but I'm still not sure what these other 'clickables' are used for....

LINK (that shows up in the thread title, next to the local time)
PARENT
THREAD

LJ Help wasn't much.... can anyone shed some light. I just wonder if using any of these could make reading/following threads easier. Thanks.