This tutorial belongs to the Swift series
In Swift, everything is an object. Even the 8 value we assigned to the age variable is an object.
In some languages, objects are a special type. But in Swift, everything is an object and this leads to one particular feature: every value can receive messages.
Each type can have multiple functions associated to it, which we call methods.
For example, talking about the 8 number value, we can call its isMultiple method, to check if the number is a multiple of another number:
A String value has another set of methods.
A type also has instance variables. For example the String type has the instance variable count, which gives you the number of characters in a string:
Swift has 3 different object types, which we'll see more in details later on: classes, structs and enums.
Those are very different, but they have one thing in common: to object type, we can add methods, and to any value, of any object type, we can send messages.