title: Why should I use a domain for l18n?
body: <p>I'm creating a WordPress theme, and I'm wondering why I should even use a domain parameter for my calls to __() and _e()? Can't I just use the default domain; what will happen if I use the default domain? What happens when I do use a custom domain? Is it just so that you can choose two different languages for two separate themes? Why would I need that? Please someone explain what this domain is for and how it's used.</p>
  
  <p>Please don't just send me links to the codex. I'd really appreciate it if someone could just be straight forward and explain it out right. Thanks. :)</p>