best seller means best seller, in English. It is considered an extremely popular book among readers, as well as being included in the bestseller list in the publishing market. Best sellers are usually considered mass literature, that is, to an audience called semi-cultured by critics.
Initially, bestsellers were used to label the best-selling works of literature in the US, and now the expression is used all over the world, from novels and thrillers to technical books, manuals etc. The best seller is defined only by its sales volume, and by its acquired fame, in addition to its adaptations and translations into other languages, the number of editions and revisions, its wide exposure in the mass media etc.
Regardless of the literary quality of the work, consumers usually perceive this type of work as being from good quality deducting that if the book sells a lot it should probably be good, but many critics say the contrary.
There is no magic formula for writing a bestseller, but usually a large part is inspired by movies, documentaries and even other books.