Most of have heard that al dente means firm to the tooth; but that's pretty broad and subjective, if you think about it. Basically, you want the pasta to feel firm and slightly resistant (almost springy) when you bite it, but not at all hard or brittle. If it sticks to your teeth when you chew it, it's not ready. resist the temptation to throw spaghetti at the fridge or the walls to see if it will stick—as much fun as this is, it will not tell you anything useful about the state of your noodles.

A good way to measure the doneness of pasta is to bite a piece in two. As well as evaluating how it feels in your mouth, look at the cross-section of the piece you bit. If the center shows a dry white core, it's not done. Some people define al dente as the moment when the pasta shows the tiniest dot of white at the core. Some say it's the moment when the white dot disappears. Go by your own sense of what's good, but watch out for overcooking—scotta, in Italian—which really ruins the pasta, turning it limp, flabby and pasty.