A newspaper's circulation is the number of copies it distributes on an average day. Circulation is one of the principal factors used to set advertising rates. Circulation is not always the same as copies sold, often called paid circulation, since some newspapers are distributed without cost to the reader. Readership figures are usually higher than circulation figures because of the assumption that a typical copy of the newspaper is read by more than one person.
In many countries, circulations are audited by independent bodies such as the Audit Bureau of Circulations to assure advertisers that a given newspaper does reach the number of people claimed by the publisher. There are international open access directories such as Mondo Times, but these generally rely on numbers reported by newspapers themselves.
In many developed countries, newspaper circulation is falling due to social and technological changes such as the availability of news on the internet. On the other hand, in some developing countries circulation is increasing as these factors are more than cancelled out by rising incomes, population, and literacy.