What are 'hash tags' and how are they used?

[Leslie]

I dont do the social media thing, but now I am seeing on commercials all these '#words' displayed everywhere. I even heard them on radio commercials ("Now all I have to do is look for hashtag money")

What does it all mean? Where do you enter those at? how are they used?

[Mir Quasem]

A hashtag is a word or a phrase prefixed with the symbol #. It is a form of metadata tag. Short messages on microblogging and social networking services such as Twitter, Tout, identi.ca, Tumblr, Instagram, Flickr, Google+ or Facebook may be tagged by putting "#" before important words, as in:

#Wikipedia is an #encyclopedia that anyone can edit.

Hashtags provide a means of grouping such messages, since one can search for the hashtag and get the set of messages that contain it.

[Ian]

Hashtags are a twitter thing. You enter them in twitter its like #summer.
Its just some stupid thing twitter came up with, -># is a hash tag!!