ELI5: Explain Like I'm 5

Chess opening book (computers)

A chess opening book for computers is like a special guidebook that tells a computer how to start playing chess based on the position of the pieces on the board at the start of the game. It is kind of like when you play a video game with a strategy guide that tells you what moves to make and when.

This opening book tells the computer what moves to make early on in the game to give it the best chance of winning. The computer "reads" the book and follows the suggested moves until it "runs out" of the book and has to start thinking on its own.

The opening book is made up of lots and lots of different chess games that have been played before by real people. Each game is recorded move by move and put into the book so that the computer can use this information to make informed decisions about what moves to make for different positions on the board.

The more games that are put into the opening book, the better the computer gets at understanding and anticipating different moves and strategies from its opponent. With a good opening book, the computer can start the game with a strong foundation and have a better chance of winning!