Allows you to group a series of statements together to perform a specific task
Functions are used to promote “code reuse”
You can control when functions are executed, for example - you can write functions that only get executed (or called) when a user clicks a specific button
// a simple function that greets you with a 'Good Morning' alert
// 1) Declare a function named greeting
function greeting(){
alert('Good Morning');
};
// 2) Call (or run) the function
greeting();