Why do people type #playingball? What does the # mean?

[MissyM]

No not number. People type on Facebook, #motivation. #ibleedpurpleandgold....etc

[dmartin2214]

The symbol stands for "number"

[Intellectualweek637]

it's a "hashtag". on twitter, if you add a hashtag (any phrase with the number sign before it) it's searchable for that hashtag.

For an example--A popular hashtag is #she'stooyoungforyoubro. What you do is start off the sentence with a witty remarke that goes with the end of the sentence (which is usually where the hastag goes.
so if I posted "If her profile picture is taken in a highschool bathroom #shestooyoungforyoubro"
that would be a good example of how it works.
then, if i wanted to search for other funny ones like that, i'd either click on the blue highlighted link it becomes after i post it, or just search #shestoyoungforyoubro and read them there.
here's the link...
http://twitter.com/#!/search/%23shestooy...gforyoubro