title: What does the dollar sign ($) mean in x86 assembly when calculating string lengths like "$ - label"?
body: <p>For example, if we were writing a simple hello world type program, the .data section might contain something like:</p>
  
  <pre><code>section .data
  
  msg     db      'Enter something: '
  len     equ     $ - msg
  </code></pre>
  
  <p>What does the $ in this example represent, and why does <code>$ - msg</code> equal the length of the string?</p>