so i'm a little new at twitter,can some one tell me what is a hash tag and specifically how to use it?

[Hazard]

i've put #AGT before on my twitter but its not highlighted blue(it's not a link to anything)but when i type in #AGT on twitter,it opens,a little help?

[AAAA]

you usually use hash tags for side thoughts like "this day is so slow #hurryup "

[Jordan]

What the guy above me said, its like "emotions" with other websites like myspace's Faces, It just shows a little more detail on how you feel, or what ever you wanna put.
Work was so boring today. #GladItsOverThough
Hash Tags always go after your last sentence. They don't use Punctuation, so they have to be one long stream of words. No periods at the end either.

[John Z Wetmore]

Hash tags are a sequence of letters and numbers without gaps preceded by the hash mark, #. You can click on a hash tag to see recent tweets that used that hash tag, or you can do a search for a hash tag to see the same tweets.

Hash tags are used to make tweets part of a conversation about some topic. For example, #AGT is used by people tweeting about America's Got Talent. However, there are no hash tag police, so #AGT is also used by people tweeting about Australia's Got Talent.

Hash tags are also used to promote a conversation about a particular event, such as a concert or a conference. For example, at the National Bicycle Summit earlier this year, the hash tag #NBS12 was used by participants. They will come up with a new hash tag next year.