title: How variables save non-scalar data
body: <p>I am a bit confused as to how variables store data of a text file into memory. </p>
  
  <p><strong>EXAMPLE:</strong> </p>
  
  <pre><code>&lt;?php
  $varContent  = 'book.txt'; 
  </code></pre>
  
  <p>Now, what I would like to clear out is that, what gets stored in <code>$varContent</code>? is the the simple string name <code>'book.txt'</code> or does the file type, header, information inside the file gets stored in the variable? </p>
  
  <p>And what the negative sides (if any) of storing a files entire content with a variable, does it break some convention or is it completely acceptable? </p>
  
  <p>To further clarify my point, if I indeed stored a file destination as shown above to a variable, and I used this variable all over inside my class, is there some sort of memory constraint or performance problem? Because, I am under the impression that assigning string/int to a variable is fine because, the memory footprint is small, but calling here and there, a 5MB .txt file may not. </p>
  
  <p>So, I'm just tying to understand this a little better. 
  thanks.</p>