A race is a grouping of humans based on shared physical or social qualities into categories generally viewed as distinct by society. The term was first used to refer to speakers of a common language and then to denote national affiliations. By the 17th century the term began to refer to physical (phenotypical) traits. Modern science regards race as a social construct, an identity which is assigned based on rules made by society. While partially based on physical similarities within groups, race does not have an inherent physical or biological meaning.