Angel hair pasta is a long, thin dried pasta, in essence a very thin spaghetti. It's best paired with light, olive-oil-based sauces.
Substitute other thin strands, such as spaghetti or the even thinner spaghettini.
Boil in abundant well-salted water until just al dente; the delicate strands will continue to cook off the heat in the sauce and you don't want to overcook them.
Dried pasta will last just about indefinitely in the pantry.