A bestseller is a book that is identified as extremely popular by its inclusion on lists of currently top selling or frequently borrowed titles that are based on publishing industry and book trade figures and library circulation statistics and then published by newspapers, magazines, or bookstore chains. Some lists are broken down into classifications and specialities (number one best selling new cookbook, novel, nonfiction, etc.). The New York Times Best Seller list is one of the best-known bestseller lists for the US. The New York Times Best Seller list tracks National and Independent book stores, as well as sales from major Internet retailers such as Amazon and Barnes & Noble. Another well-regarded list is published by Publishers Weekly.
In everyday use, the term bestseller is not usually associated with a specified level of sales, and may be used very loosely indeed in publisher's publicity. Bestsellers tend not to be books considered of superior academic value or literary quality, though there are exceptions. Lists simply give the highest-selling titles in the category over the stated period. Some books have sold many more copies than contemporary "bestsellers", but over a long period of time.
Blockbusters for films and chart-toppers in recorded music are similar terms, although, in film and music, these measures generally are related to industry sales figures for attendance, requests, broadcast plays, or units sold.
Particularly in the case of novels, a large budget, and a chain of literary agents, editors, publishers, reviewers, retailers, librarians, and marketing efforts are involved in "making" bestsellers, that is, trying to increase sales.
Read more about Bestseller: Early Bestsellers, Description and Types of Bestseller, The Making of A Bestseller, Cultural Role