On twitter, what does it mean if you put # then words after?

[xoxogossipgirl]

Please?

[RED_]

its a way to tag the words that come after it. if you click on it you will find every tweet that has that word in it. Its a way to get that word trending.

[TStodden]

is a "hash mark" in Twitter lingo... which is commonly used to denote special topics on Twitter & make it easier to search for common stuff.

For example, #ff is commonly used for "Follow Friday"

#food would be for all food-related stuff.

Hope this helps!