What Does This Symbol Mean Before A Word?

[Matty]

The hashtag refers to the topic or theme of the statement before the hashtag, it was a method created by Twitter and adopted by everyone else. On Twitter you can use # to find who's talking about a specific statement or cause.

So if there is a campaign called #iLikePie, then everyone would type their tweet and add #iLikePie at the end and then you can see everyone who's talking about the campaign. (That's just an example).