Cannot find external module 'angular2/angular2' - Angular2 w/ Typescript

Question

I am going through the step by step tutorial on angular.io (Angular 2). I am using typescript. I get the following error when trying to compile:

Cannot find ex

Answer 1

Why is this error occuring?

make sure you have this file : https://github.com/borisyankov/DefinitelyTyped/blob/master/angular2/angular2.d.ts included in your project (recommend using tsconfig.json : https://github.com/TypeStrong/atom-typescript/blob/master/docs/tsconfig.md)