Imagine a big book all about the first few moves you make at the start of a game of chess. This special book is called a Chess Opening Book. It has lots of different suggestions for how to start the game, and it tells you which moves are good and which moves are not so good.
When people play chess, they usually have some favorite moves that they like to use to start the game. But if they want to get better and win more often, they can use a chess opening book to learn new and better ways to start the game.
The chess opening book is like a menu at a restaurant. Just like how the menu tells you all the different types of food you can eat, the chess opening book tells you all the different ways you can start a game of chess.
By using a chess opening book, players can make sure they are choosing the best moves at the start of the game. It can help them be more successful in the game and maybe even win more often.