title: Why do so many sites disallow the use of non-alphanumeric characters in passwords?
body: <p>When going through registration, a lot of sites will disallow the use of symbols in passwords. This drives me up the wall from a usability perspective since I include multiple symbols in all my passwords, and as a programmer that deals with web authentication from time to time, I can't figure out why it wouldn't be allowed. Am I missing something? Are they worried about SQL injection? Don't want to deal with escaping characters? Or is there something with non-Latin-alphabet characters that can mess things up?</p>
  
  <p>Similar question, about sites that restrict length <a href="https://stackoverflow.com/questions/702421/why-restrict-the-length-of-a-password">here</a>.</p>