Swift provides as with two basic constructs: Structures and Classes which are the building blocks of our code. Structures are value type. Classes are reference types.Structures and classes have the following similar characteristics:

• We can define methods
• We can define properties
• We can define subscripts
• We can define initializers
• We can extend them to perform additional functions
• We can make them conform to any protocols as needed

In addition to the above aspects, Classes also have the following characteristics:

• We can define deinitializers
• We can perform type casting
• We can inherit properties and methods from another class(Inheritance)
• We can perform reference counting