Arrays are a very common component of modern programming languages and can be found virtually in all modern programming languages. In Swift, arrays are an ordered list of objects of the same type. This is different from the NSArray class in Objective-C, which can contain objects of different types.

When an array is created, we must declare the type of data to be stored in it by explicit type declaration or through type inference. Typically, we only explicitly declare the data type of an array when we are creating an empty array. If we initialize an array with data, we should let the compiler use type inference to infer the most appropriate data type for the array.

Each object in an array is called an element. Each of these elements is stored in a set order and can be accessed by its location (index) in the array.