Follow Friday is when, on a Friday, people show each other some Twitter love, by recommending to their followers who they recommend to follow. It was invented by Twitter users. And it’s usually preceded by the hash sign – as in #FF or #FollowFriday. So, it’s actually a hashtag, used on Fridays!
A note about hashtags, while I am at it
When you put a hash sign next to a word on Twitter, it becomes clickable. Any spaces or punctuation marks will “break” the hashtag and it will be just the word before the hyphen or apostrophe or space which is clickable.
I can only guess this, it’s a nice end of the week thing to do. Friday is a more relaxed day. People have Pizza Friday and Beer Friday, there are songs written about Friday, it all kind of goes with that Friday feeling.