Jacquard is an umbrella term that covers multi-colored knitting in which the yarn is carried across the back (in other words,
intarsia.
Fair Isle and stranded knitting are forms of jacquard, and the video that ContiKnitter mentions is a good introduction.
For more on the subject, Montse Stanley's book, "Knitter's Handbook" is an excellent sourse of information. She even includes two-sided jacquard, which sounds like a oxymoron, but isn't.