Syntax is a computer festival, dedicated solely to the demoscene, held in Melbourne.
Syntax is a "demo party". In other words,
-> it is an opportunity to enter your work into competitions for demos, music, graphics, and animations
-> a chance to chill out and watch demos; to listen to demomusic and to hang out / meet with other demosceners
-> a place where you can get back to your computery roots; to again enjoy that trusty old computer you grew up with
-> a place to find out more about realtime animation, tracked music, and what this demoscene stuff is all about
A demoparty has an emphasis on creativity with computer code, graphics and music. Depending on size, a few (or a few hundred of) visitors bring their computers and set them up on location. Attendants are encouraged to compete in shceduled competitions (referred to by demosceners as 'compos'). Spread across the duration of the event, these compos are categorised in a way that allow the attendants to showcase their artistic talents with the use of computers.
In short: a demoparty is a real-time multimedia arts festival that usually lasts for several days. Except you make the art!