After lots of speculation, Facebook have confirmed that they will be introducing hashtag functionality to their platform.

Currently the world uses the # symbol on Twitter to associate a keyword or phrase – a comment or feeling  – to their tweet. A comment or feeling others may also add to their tweets. These hashtags then let Twitter know what’s commonly being talked about – or “trendingâ€.

For example, last weekend there may have been a lot of people including #BGTfinal for the Britain’s Got Talent final in their tweets. Twitter could see how many tweets had that tag in them and so know that a lot of people were talking about it.

It’s other key purpose is that users can click on the hashtag where they see it to see other tweets with that same tag in it. So you can see what everyone’s saying about a topic. This is great for individuals who want to know what others think about current affairs, and for brands or companies running a discussion or competition on Twitter. For example, I heard Sara Cox on Radio 1 last week asking people to let her know what was in their pocket by tweeting a message with #inmypocket (I’m pretty sure that was the point of the game – it was very similar anyway!).

# have been used for a while on Facebook – but incorrectly. Sometimes they crop up because users might share their updates across social networks, so things they write on twitter automatically appear on Facebook. Meanwhile other people maybe didn’t really understand the Twitter connection and used them anyway. And some people just use them because they can be funny – they’ve almost become a new emoticon (eg. smiley faces etc.).

We don’t know when exactly the # will be coming to Facebook but it will be rolled out soon. Then Facebook will know what’s “trending†and you’ll be able to click on phrases when you see them hash tagged in posts to see an aggregated feed of other posts with that phrase.