Book excerpt: Do-It-Yourself Multiplayer Java Games: An Introduction to Java Sockets and Internet-Based Games is the fourth book of the Do-It-Yourself Java Games series. The previous books introduced games you could play by yourself or against the computer. This book will teach you to use Java sockets and TCP/IP to create games to play with your friends within a home network or over the internet. You'll learn to create games for any number of players, games that will pair up any two players, and games that restrict who is allowed to play. This book will guide you to create seven complete games: a turn-based strategy game, a timed competition, a continuous motion game, a fast-paced action game, and more.This book assumes you already have strong Java programming skills. This book assumes you either have experience creating event-driven user interfaces with Java Swing or you have read the second book, More Do-It-Yourself Java Games: An Introduction to Java Graphics and Event-Driven Programming. This book also assumes you either have experience with Java Threads and abstract classes or that you have read the third book, Advanced Do-It-Yourself Java Games: An Introduction to Java Threads and Animated Video Games. The Do-It-Yourself Java Games series of books uses a unique "discovery learning" approach to teach computer programming: learn Java programming techniques more by doing Java programming than by reading about them. Through extensive use of fill-in blanks with answers at the back of the book, you will be guided to write complete programs yourself, starting with the first lesson. You'll create puzzle and game programs and discover how, when, and why Java programs are written the way they are.