scope

Swift supports following scopes:

• modules scope - everything that declared inside module
• class scope - everyhing that declared within class/structure/enum body
• local scope - everything that declared within function or method body
• block scope - anything declared within the curly brackets {}

modules

A module is a single unit of code distribution—a framework or application that’s built and shipped as a single unit and that can be imported by another module with Swift’s import keyword.