Every programming language needs to name a piece of information so that it can be referenced later. This is the fundamental way in which code remains readable after it is written. Swift provides a number of core types that help you represent your information in a very comprehensible way.
Swift provides two types of information: a constant and a variable:
// Constant let pi = 3.14 // Variable var name = "Sarah"
All constants are defined using the let keyword followed by a name, and all variables are defined using the var keyword. Both constants and variables in Swift must contain a value before they are used. This means that, when you define a new one, you will most likely give it an initial value. You do so by using the assignment operator (=) followed by a value.
The only difference between the two is that a constant can never be changed, whereas a variable can be. In the preceding example, the code defines a constant called pi that stores the information...