Variables are used to store values, they act as containers.
x = 5;
5 is stored in
var x = 5;
x is declared as variable, and value of
5 is assigned to it.
x can be redeclared in the same block.
const x = 5;
x is declared a constant, and the value once assigned, cannot be changed.
let x = 5;
x is assigned a value of
5, and the
x cannot be redeclared in the same block-scope.
a = 4; b = 2; c = a + b;
Variables can be used in expressions like
a + b. Values of
b are substituted in place of them.