Size
"The Bible" has been thought to have sold as many as 6 billion copies in the more than 2,000 years that it has existed. "The Quran" may have just as many sales but most estimates fall far short of 6 billion copies and land somewhere within the range of 1 to 2 billion. The Communist Revolution in China put a trio of books in the top sellers ever, as books containing quotations, poems, and articles by Chairman Mao Zedong have sold countless millions of copies, with his "Little Red Book" comprised of his quotes likely at least a billion seller.
Identification
Reference books such as dictionaries and handbooks have recorded incredibly large sales over the years. "Xinhua Zidian" (The New China Character Dictionary) has sold probably 400 million separate copies since it was first published in 1957. Versions of "Webster's Dictionary" have sold a combined 100 million books according to most best selling book lists. " Scouting for Boys: A Handbook for Instruction in Good Citizenship", commonly known as the Boy Scout Manual and published first in 1908 can boast over 150 million in sales. "The Guinness Book of World Records" , first out in 1955, has sold almost 100 million times, with various spelling books and textbooks having sold in similar numbers to schools over the decades.
Time Frame
Perhaps the novel that has been bought by more people than any other is the Spanish work "Don Quixote", written by Miguel de Cervantes around 1605. It may have sold as many as half a billion copies. Charles Dickens wrote "A Tale of Two Cities" in 1859 and it is near the top of the best selling books of all time at nearly 200 million sold. J. R. R. Tolkien penned and then had published "The Lord of the Rings" in 1955, probably never dreaming it would sell over 150 million times.
Types
The world's undisputed best selling mystery novel is Agatha Christie's "And Then There Were None", written in 1939. It has sold over 100 million copies. J. D. Salinger's "The Catcher in the Rye" is required reading in high schools throughout the United States, a tale of teenagers growing up; it has sold 65 million copies. Dr. Benjamin Spock has claim to the title of most books sold about child rearing as his "The Common Sense Book of Baby and Child Care' weighs in with 50 million copies since its 1946 debut. The 1877 novel "Black Beauty", with 50 million copies sold, is the top book that has an animal as the main character.
Considerations
Books such as "Gone with the Wind", "Valley of the Dolls", and "To Kill a Mockingbird" all have sold at least 30 million times. Children stories such as "Charlotte's Web" and "The Tale of Peter Rabbit" are over 45 million. The Harry Potter books written by J.K. Rowling are wildly popular, with "Harry Potter and the Philosopher's Stone" and "Harry Potter and the Sorcerers Stone" selling well over 100 million. In comparison the best selling "Da Vinci Code" by Dan Brown, sold fewer than 60 million copies.