This section will talk about the go/scanner, go/parser, and go/token packages, as well as the go/ast package. This is low-level information about how Go scans and parses Go code that will help you to understand how Go works. However, you might want to skip this section if low-level things frustrate you.
Parsing a language requires two phases. The first one is about breaking up the input into tokens (lexical analysis) and the second one is about feeding the parser with all these tokens in order to make sure that these tokens make sense and are in the right order (semantic analysis). Just combining English words does not always create valid sentences.