Precut Squares come in various sizes are sometimes called Layer Cakes or Ten Squares (10" squares), and the smaller ones are called Charm Squares (5" squares). Mini Charms are 2 1/2" squares.
Fabric Strips, sometimes called Jelly Rolls, Roll Ups, Honey Buns, Jewels, and Crackers, are a great way to get many different colors in one packet or roll. Many patterns are "pre-cut friendly" and are designed for 2 1/2" or 1 1/2" strips.