A ream is a unit of measurement used to quantify paper. Typically, a ream consists of 500 sheets of paper, although some types of specialty paper may have different quantities. Reams are commonly used in offices, schools, and printing industries to standardize the sale and distribution of paper products. In addition to standard paper, reams can also refer to other materials, such as cardstock or photo paper. The term is often used in conjunction with paper sizes, such as letter or A4, to specify the type of paper being purchased or used in various applications.