Bechamel is a standard white sauce and one of the five mother sauces of classical cuisine. That means it's the starting point for making other sauces, called "small sauces." Here's a list of small sauces that are based on bechamel.
A traditional bechamel is made by whisking hot milk into a simple flour-butter roux. The sauce is then simmered with onion, cloves and nutmeg until it is creamy and velvety smooth.