(aka the Double Cast-On or Continental Cast-On)
These instructions will teach you how to use the long-tail cast-on technique. There are many different ways of casting on stitches for a knitting project, and, to some degree, the technique you choose should depend on the type of project you're planning. Certain cast-ons are better bases for different stitch patterns, others are best for creating perfect edges on a garment. The long-tail cast-on is a great basic technique: it's relatively easy for beginners to learn, it creates a clean but stretchy edge, and it's the fastest cast-on around (once you get the hang of it).