Basically web servers have a series of codes that they return for specific errors... 404 = couldn't find the page you were looking for, 403 = while I found the page you asked for, I'm not allowed to give it to you. The reasons could be that you requested a restricted page, that you lack sufficient user rights to access the page. My guess is you tried to access runescape through an old direct link rather than through the main http://www.runescape.com page. Which is why I asked what the exact URL you tried to access was.