Chess Terms
Book Move

Book Move

The term "book move" is used often in chess broadcasts, chess news, and chess articles, but what does it mean? Let's find out what a book move is and why it is important!

Here is what you need to know about book moves:

What Is A Book Move?

A book move is a move that is well-known to opening theory. In other words, a book move is an opening move that is considered standard or conventional.

The term book moves relates to the time that almost all opening theory was once contained in only books (although this information is now readily available in multiple formats like opening databases, videos, and other online material as well as books). Chess books on openings still exist, of course, and some have been around for over 100 years. Modern Chess Openings (MCO) has had 15 revisions since it was initially published in 1911.

book move chess
The second edition of MCO, published in 1913. Photo: Wikimedia.

Opening theory refers to known opening moves that have been published in books, databases, magazines, etc. If two players play a game whose first 10 moves have been played before, then those first 10 moves are considered book moves or theory. If you ever hear someone say that a player is "booked up" on a particular opening, they are simply saying that the player knows the theory.

When you analyze a game in, some moves are labeled as "book"—this is also referring to book moves.

book moves chess analysis clearly labels book moves.

Why Are Book Moves Important?

Book moves are important for several reasons. If a player knows book moves in a particular opening, it means that they know the opening theory for the position that they are playing. Thus the player understands the known plans associated with the opening that they are playing as well as where their pieces should be placed.

When a player deviates from opening theory, they are considered to be "out of book." After both players are out of book and no longer playing book moves, the players are essentially playing for themselves at that point and are no longer playing from memory.  The number of book moves played can also indicate the originality of the opening phase in a game. In some games, both players follow theory or play book moves for 20 to 30 moves, but leave known theory in other games after only a couple of book moves. 

Book Moves On

In essence, the number of book moves indicates how much theory was known by the players in a specific game—this knowledge is incredibly important when analyzing your games, as it gives you insight into where your opening knowledge ended and tells you exactly where you should start studying your openings. made this process very easy by placing the openings tool directly in Simply navigate to the "Openings" tab when analyzing a game.

book moves chess
Moving from analysis to openings is very easy on

The opening tool in shows lots of important information. It displays the total number of games in the database from the current position, the winning and drawing percentages for different moves in the position, and the number of times a move has been played in that position. As mentioned, when analyzing a game on, specific opening moves are labeled as book moves.

book moves chess
Book moves are clearly labeled on

If you have a game where you got into trouble in the opening, you can use the analysis tool to figure out exactly where the problems begin. The next step would be to select the openings tab (as explained above) or to head over to Explorer, where you can check your moves with's opening database.

book moves
Explorer is a fantastic way to learn about openings by browsing through's opening database.


You now know what book moves are, why they are important, how to study book moves on, and more! If you still want more information on a specific opening you play or an opening that was played against you, you can head over to to get "booked up" and learn more.

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