Can anyone explain hashtags?

[Amelia]

Ok so im always seeing facebook comments and stuff with all these hash tags (eg #bestfriends )
What do these mean??

[Patrick]

Think about it this way. You are walking on the beach, if you think its sunny you write #hot or #sunny.
It pretty much is like a status of some sort. So, if you were with your friends you would say: With friends #fun or #awesome. It comes from Twitter and it is beyond me why people started doing it on Facebook. Hope this helps.

[Jake]

The # symbol, called a hashtag, is used to mark keywords or topics in a Tweet. It was created organically by Twitter users as a way to categorize messages.

People use the hashtag symbol # before a relevant keyword or phrase (no spaces) in their Tweet to categorize those Tweets and help them show more easily in Twitter Search.
Clicking on a hashtagged word in any message shows you all other Tweets marked with that keyword.
Hashtags can occur anywhere in the Tweet – at the beginning, middle, or end.
Hashtagged words that become very popular are often Trending Topics.

Example: In the Tweet below, @eddie included the hashtag #FF. Users created this as shorthand for "Follow Friday," a weekly tradition where users recommend people that others should follow on Twitter. You'll see this on Fridays.

[Terence]

Hashtags are words or phrases prefixed with the symbol #,[1][2] a form of metadata tag. Also, short messages on microblogging social networking services such as Twitter, may be tagged by including one or more with multiple words concatenated.
#Wikipedia is an #encyclopedia
Hashtags provide a means of grouping such messages, since one can search for the hashtag and get the set of messages that contain it.