A Module is a collection of methods and constants. The methods in a module may be instance methods or module methods. Instance methods appear as methods in a class when the module is included, module methods do not. Conversely, module methods may be called without creating an encapsulating object, while instance methods may not. (See Module#module_function)
In the descriptions that follow, the parameter syml refers to a symbol, which is either a quoted string or a Symbol (such as :name).
module Mod include Math CONST = 1 def meth # ... end end Mod.class #=> Module Mod.constants #=> ["E", "PI", "CONST"] Mod.instance_methods #=> ["meth"]