Anybody know what the "#(insertphrasehere...)" things mean?

[HelpMeRiteNow!!!!!!]

On facebook, people keep commenting on stuff with a # and then put a phrase or word after it...

Ex.
(status) Anyone wanna be on my bball team?
(comment1) me!
(comment2) no.
(comment3) im in..
(comment4) SOLID
(comment5) #dreamteam


Like that. What does that mean?

[Holy Smokes =)]

It's a twitter hashtag -___- people put it before stating a feeling/personal status.
Example: "puttng on scarf, cap, and mitts #coldweather "
OR, "made a new team with _______, ________, and ________ #wethebest."

[Frank]

That's a hashtag. See my source for an explanation. Sometimes they are used sarcastically.