Why does a url use ://?
jacquesm: The ':' is to separate the scheme from the bits that are specific to the scheme. The // is to indicate a hostname and not a directory. http:/test is a valid url indicating a relative path on the machine that the current resource came from, http://test is a url that specifies a resource on a machine mapped to the TLD test. The double slash removes the ambiguity. It really is two bits, a ':' and the '//'Other possible sources of confusion:http://test.com:80/You could then get:http:/test.com:/Position would give it away, but, if you then complicate matters further by using default protocol (in your broweser http) it looks like::/test.com:/In many browsers://test.com:/ is perfectly legal.Of course, you could strip that down further by dropping the default port colon to get:://test.com/See here for a much longer (and probably better :) ) explanation:http://tools.ietf.org/html/rfc1738I hope that helps !