What is the main usage of index.d.ts in Typescript? : <p>I have seen some projects declaring all the types in <code>index.d.ts</code>. So that the programmer do not need to explicitly import the type from other files.</p>

<pre><code>import { TheType } from './somefile.ts'
</code></pre>

<p>Is that the correct usage of <code>index.d.ts</code> file? I'm not able to find anything in the official documentation.</p>
