There are two ways to get Type Definition files ( also known as Typings ) in your project

1. Use @types scoped packages from NPM

Starting with TypeScript 2, Typings can automatically be loaded from NPM packages.

If for example you use lodash, you can install npm install @types/lodash and the types are loaded automatically. The definition files that are in these packages are loaded form the same place as

I did some tests, it looks like type definitions are found if you do import _ from 'lodash'; but not if you do import _add from 'lodash/add';.

It seems packages with nothing after the package name are taken in account but nothing else.

2. Create your own *.d.ts file

You can create your own definition files using the Official documentation.