title: What is context in elixir phoenix html generator
body: <p>I wanted to have a look at phoenix <code>1.3-dev</code>. I clone phoenix from <a href="https://github.com/phoenixframework/phoenix" rel="nofollow noreferrer">repository</a> and followed the <code>phoenix/installer/README.md</code> to build archive.</p>
  
  <p>phoenix/installer/README.md (for reference)</p>
  
  <pre><code>$ cd installer
  $ MIX_ENV=prod mix archive.build
  $ mix archive.install
  </code></pre>
  
  <p>I created a new phoenix app by <code>mix phx.new blog</code> but when i tried to create a simple html scaffold by <code>mix phx.gen.html Post posts title body:text</code> then i get following error message:</p>
  
  <pre><code>** (Mix) Expected the schema argument, ":\"Elixir.Company.companies\"", to be a valid module name
  
  mix phx.gen.html and mix phx.gen.json expect a context module name,
  followed by singular and plural names of the generated resource, ending
  with any number of attributes:
  
      mix phx.gen.html Accounts User users name:string
      mix phx.gen.json Accounts User users name:string
  
  The Accounts context serves as the API boundary for the given resource.
  Multiple resources may belong to a context and a resource may be
  split over distinct contexts (such as Accounts.User and Blog.User).
  </code></pre>
  
  <p>My question is why should add a <code>context</code> module? how and where it helps?
  if you know something about this, please describe a usecase so i can understand.</p>