A Timecode system is where your turntables are hooked up to your computer with a special record on the decks. You can then use songs from your computer, and manipulate them as if they were on that record. A lot of people use it to retain the feel of using vinyl, but use it over records because: -they can't get alot of tracks on vinyl anymore -vinyl is too expensive for them -it is easier to carry around a laptop than a crate of records They are just some of the reasons. When soldios referred to 'SL1' he is talking about a Serato SL1 Box. It is one timecode soundcard that you can buy which will do what i said above. The main two timecode systems that most use are either made by serato or traktor. To give you a basic idea on how it works, here is a (basic) diagram: EDIT: got beaten to it, but will post anyway so you can see the diagram and some advantages