Chapter 6 - Variables and Constants

• Variables are nothing but reserved memory locations to store values.
• The value of a constant can’t be changed once it’s set, whereas a variable can be set to a different value in the future.
• Declare constants with the let keyword and variables with the var keyword.
• Constant and variable names can’t contain whitespace characters, keywords, mathematical symbols, arrows, Unicode code points.

You can provide a type annotation when you declare a constant or variable, to be clear about the kind of values the constant or variable can store. Write a type annotation by placing a colon after the constant or variable name, followed by a space, followed by the name of the type to use.

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