Why Does a Web Address Need “://”? Uncovering the Truth Behind URI Slashes

When we browse the web we type URLs that start with http:// or https://, such as http://honeypps.com. What purpose do the "://" or "//" serve?

To understand this we need to discuss URIs. A Uniform Resource Identifier (URI) marks resources on a server and is often seen in a browser’s address bar. Strictly speaking, a URI includes both URLs (Uniform Resource Locators) and URNs (Uniform Resource Names).

Because URLs are so widely used, in everyday conversation URI and URL are often treated as synonymous.

URI format:

URI = scheme:[//authority]path[?query][#fragment]
authority = [userinfo@]host[:port]

The diagram below illustrates the structure:

The first part, scheme , indicates the protocol (e.g., http, https, ftp, file). After the scheme comes the three characters “://”, separating the scheme from the authority.

The authority part specifies the host name and optional port (host:port). Historically it could also include user info (user:passwd@), but this is rarely used today.

When interviewers ask “what’s the use of //?”, they often aim to probe deeper understanding.

In October 2009, Tim Berners‑Lee admitted that the initial double slashes in web addresses were unnecessary. He said he could have designed URLs without them and called the decision a “good idea at the time”.

He later clarified that the “//” has no real function in the URI syntax.

Indeed, the “//” in a URI is essentially superfluous.

Tim Berners‑Lee, the inventor of the World Wide Web, has contributed immensely to global information exchange and chose not to patent “WWW”, making the web freely available to everyone.

References

https://en.wikipedia.org/wiki/Uniform_Resource_Identifier

https://en.wikipedia.org/wiki/Tim_Berners-Lee

http://blog.sina.com.cn/s/blog_3e4d3af301017fnr.html