This chapter does not provide a complete introduction to Go, in particular, it is not intended to replace the language description2E Rather, it deals with aspects of Go that are not directly apparent from the documentation of the Go developers, namely, how fundamental software engineering principles can be implemented in Go. The package concept is explained and it is shown how abstract data types can be realized as packages. This is followed by considerations on the concept of variables or objects and the distinction between value and reference semantics—a central point in OOP.