title: Do I need to compile the header files in a C program?
body: <p>Sometimes I see someone compile a C program like this:</p>
  
  <p><code>gcc -o hello hello.c hello.h</code></p>
  
  <p>As I know, we just need to put the header files into the C program like:</p>
  
  <p><code>#include "somefile"</code></p>
  
  <p>and compile the C program: <code>gcc -o hello hello.c</code>.</p>
  
  <p>When do we need to compile the header files or why?</p>