what is this # mean in twitter?

[mrikabat]

[Louise]

A hashtag is a word or a phrase prefixed with the symbol #, a form of metadata tag.
Short messages on microblogging social networking services such as Twitter, Tout, identi.ca, or Google+ may be tagged by including one or more with multiple words concatenated, e.g.:

#Wikipedia is an #encyclopedia

Hashtags provide a means of grouping such messages, since one can search for the hashtag and get the set of messages that contain it.

[Patrick]

Its called a hashtag. You say it when something is trending or it is a way to express how you are feeling. Example: Went to the mall today! #excited
OR: Cant wait for the new Halo game! #Halo4

Stuff like that.

[Doug]

More or less the "hashtag" is something that is a link. If I said something like this

"Hey man I'm tired, gonna hit the hay #exhausted."

basically the hashtag just pertains to whatever your talking about.

If you look up hastags say #exhausted you will find a bunch of other people talking about how they are #exhausted.

It's a great way for people to look for directly what they want

[Rabeet]

Its a hash tag # it mostly symbolises an event or action like #lumia.

[Katy Giselle]

It's called a hashtag. You use it when you are tagging something lol.

Example... Lets say I am going to bed. This will be my status: "Had a rough day at the park with my daughter. I am going to bed #sleepy # daughter #bed

It's basically what your post is about.