A variable is a value that has a name. It is defined by a declaration.

A variable is declared as follows:

let myVariable = 0;

The let keyword indicates we are declaring a variable. The name of the variable is myVariable. The value that is named is 0.

Variable names must start with a letter, may contain lowercase and uppercase letters, may also contain numbers 0-9 and underscores _.

The convention is to use lowerCamelCase for variable names.

let declarations declare immutable variables. This means the value cannot change after it is declared.

Some examples of immutable variables:

let x = 12;

let temperature = -5;

let city = "Amsterdam";

let isNotFunny = false;

A declaration ends with a semicolon ;

The convention is to use spaces around the equals sign.

The declarations above all span one line but a declaration may span several lines as long as it ends with a semicolon.