You've probably seen the cryptic letters SXSW dropped into stories and tweets over the last few days and around this time every year. If you know your iOS from your Android then you probably know only too well what everyone's bleating on about. However, if you're not quite as clued up as you'd like to be, then Pocket-lint is here to lend a hand and tell you what the hell SXSW is all about.

It may be made up of four mysterious letters when written down, but SXSW is said aloud as South by Southwest. It's a catch-all name for a set of three festivals held in Spring every year at the Austin Convention Center in Texas, USA. The venue is in the centre of the state's capital and spread out over a massive six-block radius, covering an impressive area of 881,400 square feet.

The three festivals are SXSW Music, SXSW Film and SXSW Interactive and run one after the other. The first two festivals are fairly self-explanatory, with both being breeding grounds for breakthrough bands and flicks. The Polyphonic Spree made its debut there and garnered fans before the band was even signed, while the 2009 festival played host to the US premiere of The Hurt Locker. Meanwhile, the Interactive portion of SXSW involves web startups and tech-heads from all over the world getting together to form a hive of creativity and is the part that has made the whole event become something of the CES of the online social world.

As well as concerts and film premieres, the three festivals feature all sorts of conferences, keynote speeches and panel discussions as well as meetings, demos and a trade show attended by hundreds of exhibitors. And, of course, there are the all-important parties. Outside of the event itself, plenty of unofficial networking goes on, so you never know where the big news will come from.

SXSW first started out in 1987 as a music festival and although it was expected to be a relatively small, regional event, it went national almost right away. In 1994, the SXSW Film and Multimedia Conference component was added, and then split into two separate events the following year. In 1999, the Multimedia portion was renamed SXSW Interactive and the current format was set. While 700 people turned up at the original festival, SXSW is now attended by around 17,000 people from all over the globe.

SXSW is big news in the tech world and has been particularly important to the rise of social networking with Facebook overlord Mark Zuckerberg giving a keynote interview in 2008. The 2007 festival was where Twitter first started to gain some significant ground with the #SXSW hashtag getting a serious workout, while 2009 saw the launch of FourSquare.

SXSW has inspired similar festivals including NXNE (North by Northeast) in Toronto, Canada. There isn't really a direct equivalent on this side of the pond yet, although 2011 has even seen Twitter talk of a UK version emerging. This year's SXSW is taking place 11-20 March (2011). Exact dates for the 2012 festival have yet to be set, but they should be around the same sort of time.