What is the semantics of the double slash following the scheme in a URI?

Question

According to http://tools.ietf.org/html/rfc3986 and http://en.wikipedia.org/wiki/Uniform_resource_identifier, a URI may or may not contain a double slash following the schem

Answer 1

Besides the RFC which thoroughly explains the answer, I thought you might like this quote straight from the inventor of the World Wide Web himself.

When [Sir Tim Berners-Lee] was asked what he would have done differently, the answer was easy. "I would have got rid of the slash slash after the colon. You don't really need it. It just seemed like a good idea at the time."

Source: http://www.wired.co.uk/news/archive/2014-02/06/tim-berners-lee-reclaim-the-web