title: What is the role of Angular core module?
body: <p>I read an <a href="https://medium.com/@michelestieven/organizing-angular-applications-f0510761d65a" rel="noreferrer">article</a> about organizing folders in Angular and the author uses one called <code>core</code>, in which he creates the core module and insert only services which will be called once. </p>
  
  <p>Currently, I'm working on a project whereupon I adopted the structure recommended by the <a href="https://medium.com/@michelestieven/organizing-angular-applications-f0510761d65a" rel="noreferrer">article</a>. Inside my <code>core</code> folder/module I created a module called <code>api</code>:</p>
  
  <pre><code>\app
    \core
      \api
      ...
    \shared
    ...
  </code></pre>
  
  <p>My question is: as the <code>api</code> is a module, I was wondering why not remove it from <code>core</code> and put in <code>app</code> folder?</p>
  
  <pre><code>\app
    \api
    \core
    \shared
    ...
  </code></pre>
  
  <p>Angular itself has <code>core</code> module too (where we import <code>ngModule</code>, <code>Injectable</code>...) and I'd like to know what is its role.</p>