Serato is a software development company that specializes in supplying programs used in music production and for DJing. Their main DJing program is Scratch Live, which acts as a laptop-based alternative to a set of decks. They have now launched a new beginners level piece of DJ software, Serato DJ Intro. This is a simplified version of the aforementioned Scratch Live, and will be free to download. However, it does require you to have a compliant controller already – for example one of these – which allows you to mix together music from different sources, such as a USB, CD or MP3.
Get acquainted a bit with Serato DJ Intro in the below video, and more details available here on the Serato website.