Uniform Resource Locators (URLs) are a specific form of Uniform Resource Identifiers (URI) described in RFC 2396 which updates RFC 1738 and RFC 1808. RFC 2016 defines uniform resource agents.
URIs have the form scheme:scheme-specific-part, where the schemes supported by this library are described below. See Supported URL Types.
FTP, NFS, HTTP, HTTPS, rlogin,
telnet, tn3270, IRC and gopher URLs all have the
form
scheme://[userinfo@]hostname[:port][/path]
where ‘[’ and ‘]’ delimit optional parts.
userinfo sometimes takes the form
username:password but you should beware of
the security risks of sending cleartext passwords.
hostname may be a domain name or a dotted decimal
address. If the ‘:port’ is omitted then the
library will use the `well known' port for that service when
accessing URLs. With the possible exception of
telnet, it is rare for ports to be specified, and it
is possible using a non-standard port may have undesired
consequences if a different service is listening on that port
(e.g., an HTTP URL specifying the SMTP port can cause mail to be
sent).
The meaning of the path component depends on the
service.