A bestseller is a book that sells a significant number of copies in a particular period of time. While each list has its own set of guidelines and scoring methods, most have a certain threshold of sales that a book must hit in order to make the list.
Bestseller lists are a snapshot of a week, but the actual volume of books sold to get on a specific list varies from one week to the next. For example, a book might sell many copies during Christmas and then fewer copies during the summer. Similarly, a book might sell fewer copies in the first few months of its release and then begin to sell very well.
The New York Times Best Seller List
Although the NYT is arguably the most important and influential of these curated elitist lists, it is still not actually a true best-seller list when compared to how many books sold overall in a given week. This was a major problem for William Blatty, author of The Exorcist, who sued the New York Times in 1983 because his latest book, Legion, did not appear on the Times's best-seller list.
These lists, while they may not be completely unbiased or objective, do represent a good indicator of popular literary taste and judgment. The problem, however, is that these lists are not based on scientifically sound data. In fact, it has been argued that these lists are often based on editorial decisions made by the editors.
This is a problem because the editors can favor certain types of books over others. For example, some books may be classified as literary fiction while others are categorised as non-fiction or children's books. This can lead to a wide variety of titles appearing on different best-seller lists and in various categories.
Publishers can also use these lists to help guide their marketing strategies. For instance, a book that has sold several hundred copies and has been consistently selling well over time can be used to boost sales of other books in the same genre.
Another problem is that these lists can be manipulated by scammy marketers who can help authors crank out a bad book, buy their way into these mini-categories, and then call themselves bestselling authors. This is a serious danger for first-time and unestablished authors.