What does import from '@somefolder' do : I cloned a repo from [here.][1] And I found an import stat

    import { NGSWUpdateService } from '@ngsw/ngsw-update.service';

I would like to state here that @ngsw is present inside my project's `src/client/app/shared/ngsw/ngsw-update.service`

But my question here is how does angular know where the ngsw folder is located and what is the role of `@` here I know that `~` means the root of the folder I'm working in but what does this `@` means and how does it work. I used to think that's something angular uses like @angular/core and other but its use in a local project is something not usual. 


  [1]: https://github.com/EreckGordon/angular-universal-pwa-starter-deploy