Dart has a keyword to define a library—library, as you may expect. Although optional, this keyword is very useful when creating multiple file libraries or to create documentation for libraries before publishing them as APIs.
Dart has the dartdoc tool for generating HTML documentation for Dart packages. To use this tool, we have to write comments in a specific way, and we will explore this further in the following examples.
Let's take a look at how to define a library using this keyword, and the multiple approaches that can be taken when creating libraries to make the correct encapsulation and to make library usage more concise.