This book requires a computer running a Unix variant with a relatively recent Go version, which includes any machine running Mac OS X, macOS, or Linux.
Apple used to call its operating system as Mac OS X followed by the version number; however, after Mac OS X 10.11 (El Capitan), Apple changed that, and Mac OS X 10.12 is now called macOS 10.12 (Sierra) - in this book, the terms Mac OS X and macOS are used interchangeably. Additionally, there is a big chance that by the time you read this book, the latest version of macOS will be macOS 10.13 (High Sierra). You can learn more about the various versions of macOS by visiting https://en.wikipedia.org/wiki/MacOS.
All of the Go code in this book has been tested with Go 1.8.x running on a iMac using macOS 10.12 Sierra and with Go version 1.3.3 running on a Debian Linux machine. Most of the code can run on both Go versions without any code changes. However, when newer Go features are used, the code will fail to compile with Go 1.3.3: the book states the Go programs that will not compile with Go version 1.3.3 or require Go version 1.8 or newer.
Please note that at the time of writing this text, the latest Go version is 1.9. Given the way Go works, you will be able to compile all the Go code of this book in newer Go versions without any changes.