Paper purchase is a term used to describe the process of buying paper for printing or writing. The three words that make up this term are REAM, PAD, and QUIRE. A REAM is a unit of paper that is equal to 500 sheets. A PAD is a stack of paper that is usually bound together with glue or staples. A QUIRE is a unit of paper that is equal to 25 sheets. Together, these three words describe the process of purchasing paper for printing or writing.