JavaScript Variables can be declared in 4 ways:

1. Automatically
2. Using var
3. Using let
4. Using const

var:

1.  Function-scoped
2. Can be redeclared and reassigned

let:

1.    Block-scoped
2.    Can be reassigned, but not redeclared in the same block 

const:

1.    Block-scoped  
2.  Cannot be reassigned or redeclared