What to do when user edits and breaks the url?
<p>I have a url structure that looks something like some_page.php?id=123 and I get the id for that page and that is good.</p>

<p>But sometimes users either edit the url, or one way or another there is no id.  </p>

<p>What do people usually do in that case? Should I just redirect the person to a 404 page? Or should I return 404 from that page in case they want to correct the url? Or is 404 the right thing to do in that case?</p>

<p>Also, how do I tell where this user came from?</p>

<p>Thanks!!</p>
