On Facebook why are people putting this # in their words?

[Jonathan]

What does it mean when someone does this, #swag, for example.

[i want chocolate]

It's a hashtag. Idk about FB, but they use it on Twitter and it is just to categorize tweets. For example, if you searched "swag" you would see all the tweets where people put "#swag". Maybe their twitters are linked to their FB? Idk.

[cwalker]

its a hashtag; used in twitter.
It's like linking a 'tag' to what you're saying
Useless in facebook, but people get used to it in twitter and can't help it, or they think it's cool