What is a hash tag I don't understand?

[Hannah Bear]

Some one said its on twitter but I don't have a twitter and I don't want one what is a hash tag and can I have an example

[Tyler]

is a hash tag!

[pumpedupkicksss]

hashtag - #
it tags stuff when you put it infront of a word on twitter

[CJ]

Hashtag- The # pound sign.

[jacovkss2]

If you want to know what a #hash tag is, this is your answer. :-) See that # sign in front of hash? That sign is called a hash character (I'm pretty sure it has other names as well), and it is used to mark important words in a text. The software (twitter, in this case) uses that character to turn the whole word into a clickable link. When people click the link, they get to see all messages that have same hash tag. It's a way to cross-reference. Anyway, see the link below!

[Cherry]

this is a hashtag by itself #
a hash tag is something used on tiwtter for one of two reasons
1 used so you can tell what someone is talking about and by pressing it you can see what other people are saying about the same topic ex if you are tweeting about a tv show like Big Brother you would tweet "omg i hope rachel wins!!! #BigBrother"
2 its used for humor (as a joke) "one day its hot the next its cold #CanadianProbz" or "my maid is late #PrincessProbz"
It can also be used to get something trending (popular) for example someone can tweet "come on huys let's get #TeamPeeta trending!!!!" and then everyone else tweets about it ex: ( I LOVE the boy with the bread #TeamPeeta"

[It]

is special character.
used to recognize pattern in compiler programming.
used to inform the os of mobile for releasing exact service as required.
in other console application .it kind of warning to kernel that special request from outside.