When you're making a cloth, the "right side" is the side that you want to look at. In garments, it's the outside. The "wrong side" is the side that would be against the skin.
In stockinette stitch, knitting flat, the right side is the side you knit, and the wrong side is the side you purl. In garter stitch, both sides look the same, so the right side is generally the side you are working the odd-numbered rows. I read a suggestion somewhere that if you're not sure, to put a safety pin on one side of the work, to designate that as the right side.
When knitting in the round, the right side is the outside, and the wrong side is the inside.
edit: in before Ingrid! :happydance: :roflhard: