title: Enumerable.Where - How To Read The API
body: <p>I am trying to understand specifically why it is neccessary to have this <code>Where&lt;TSource&gt;</code></p>
  
  <p>What does the type straight after <code>Where</code> tell you?</p>
  
  <p>I understand the 'this' concept which means its an extension method but cannoth understand the type after Where </p>
  
  <pre><code>public static IEnumerable&lt;TSource&gt; Where&lt;TSource&gt;(
      this IEnumerable&lt;TSource&gt; source,
      Func&lt;TSource, bool&gt; predicate
  )
  </code></pre>