Square is a mobile payment system that allows individuals and small businesses to accept credit card payments through a small, lightweight card reader that plugs into a smartphone or tablet. Founded in 2009 by Jack Dorsey, Square has experienced rapid growth, processing over $2-10 million in payments per week. The free Square reader makes it easy for individuals like medical practitioners and small businesses like cupcake shops to accept payments. Square aims to process $1 billion in transactions in 2011 and continues improving its products and services.