This is part of the Complete Typescript Course, have a look at the complete course here - https://angular-university.io/course/typescript-2-tutorial?grpp=f&utm=ytts&couponCode=TYPESCRIPT_YOUTUBE In this lesson we are going to learn what are the different ways of declaring a variable in Typescript: we are going to take the legacy var keyword and explain a couple of problems with it, and we will then compare it to let and const. We are also going to learn how const does not ensure object immutability. For more videos tutorials on Angular, check the Angular University website - https://angular-university.io/ The Angular University Ebooks: - Typescript Jumpstart Kindle Ebook - http://amzn.to/2sGavyw Follow us: Twitter - https://twitter.com/AngularUniv Google+ - https://plus.google.com/u/1/113731658724752465218 Facebook - https://www.facebook.com/angular.university Check out the PDF E-Books available at the Angular University - https://angular-university.io/my-ebooks