Verified answer

I don't either..its just a tweet thingy..I suppose you just put it in front to show someone something idk

Hashtags are normally used to attach a tweet to a certain topic, like at the moment you might see tweets ending with #londonriots in blue text.

The most hashtagged phrases come up in the trending topics bar on the right side of the Twitter feed. They are sometimes just used to warn people about links and stuff like 'TwitterAfterDark or #NSFW, and sometimes used almost as a joke like saying something stupid you did and tagging it #Fail

It's used most of the time for the main idea of the sentence or as someone said before, because it's a trending topic. For example you say: "Yay! Just got a new xbox! #happy" :)

technically the # , is to symbolize an important word in the tweet , or it might be a trending topic .