circulation

Print circulation is the average number of copies of a publication. Number of copies of a nonperiodical publication such as a book called usually print run. Circulation is not always the same as copies sold, often called paid circulation, since some issues are distributed without cost to the reader. Readership figures are usually higher than circulation figures because of the assumption that a typical copy is read by more than one person.
Print circulation is one of the principal factors used to set advertising rates. 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, print 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.

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