have block scope like let keyword
// ES5var value = "hey";value = "Cool";console.log(value); // Cool// ES6const value = "hey";value = "Cool";console.log(value); // Error: "value" is read-only
const obj = {};obj.name = "Hemant";console.log(obj); // {name: "Hemant"}// butconst obj = {};obj = {location: "HYD"};console.log(obj); // Error: "obj" is read-only
const API_KEY = "XXX";const API_SECRET = "DDGD_DDDGG-SS";const port = 4000;const PI =3.14;