The above answers are right: knitting is done with one or two needles (pointed rods) and crochet with one or two needles with a hook or by hand with a small hook. Knitting can be done by machine, with all yarns or even fine threads. T-shirt fabric is knitted by machine. True Crochet machines have not been perfected yet; the closest approximation is really just a blanket stitch. Almost all crocheting is too intricate and is still done by hand.