What does hashtag mean?

[whisperingdoll888]

I see people on like youtube videos say hashtag (something funny here) lol, so yea, what does it mean? I believe it has something to do with twitter, but could someone explain to me in detail? Most detailed explanation gets best answer

[Foreverwandering]

U use a hashtag on twitter so that u can join in on conversations going on in twitter

[Liz]

This is a hashtag: #
But you probably already knew that.
It's usually on Twitter and it isn't really anything significant, it's just makes it a bit easier to write stuff on your phone. Like, yesterday, one of the Worldwide trends, (That means A LOT of people were talking about it), it said #HappyBirthdayDemi, as a Happy B-day to Demi Lovato.
It really doesn't mean anything at all.
Sorry, there's probably some irrelevant information in here.. Yeah.

[signaleerodayear]

The hashtag is the # symbol followed by whatever you are trying to "trend" with no spaces. It allows you to put a tag on your tweets so you can search twitter by those hashtags. For example you can "search" the hashtag YOLO by typing #YOLO . The important thing to remember is that there are no spaces. For example, here are some hashtags: #SoHappyICouldDie #BestFriendEver #ChickFilA #Adidasmakesthebestshoes etc. etc.

[Dave]

Here's an awesome guide to all of the most common bits of Twitter language (including hashtags) -http://www.bfinternet.co.uk/news-info/faq/a-beginners%E2%80%99-guide-to-twitter-jargon