What does this "#" number symbol mean?

[luv4music567]

I see it on facebook and twitter all the time. It usually has the number symbol and then some random words after it. i.e: "#hooplah"

[adette♡]

is a hash. Writing # before a word is called a 'hashtag.' On twitter, people use it to mark certain phrases or topics. Basically, it makes searching easier. For example, if you search on #LOST (or #Lost or #lost, because it's not case-sensitive), you'll get a list of tweets related to the TV show. You won't get are tweets that say "I lost my favorite sweater" because "lost" isn't preceded by the hash tag.

So hashtagging words has just become a thing people do on twitter (and it's carried over to facebook, where it doesn't really do anything.) To be honest, I'm not sure why people do it on facebook (except for people whose twitter updates are linked to their status updates, of course) ...

hope this helps ♥