What does it mean when somebody types # after in texting?

[Dovahkiin]

Like they'll say "I had a good time last night #Fun times"

My friends/cousins etc Keep doing it and its annoying. I asked them what it means but they wouldn't say.

[lisa]

It's a hashtag for Twitter.

[mariana]

It does not mean really anything it's just something everyone uses on twitter no worries it means the same as you read it "I had a good time last night #Fun times" = "I had a good time last night IT WAS FUN"

[Amy Smith]

Its the hashtag on twitter so when you click on it you can see what everyone else is saying and then possibly make new friends, it annoying how people have started using it in texts and on facebook and everything, just leave it for twitter. makes me angry lol