An application-level protocol used to obtain resources on the Internet. Following are some of the common URI schemes, all of which ride over TCP/IP. See URI and URL.

  URI Scheme

  Prefix    To gain access to

  http:     Web server
  https:    secure Web server
  ftp:      file server
  mailto:   sending e-mail (SMTP)
  im:       instant messaging

  news:     Usenet newsgroups
  nntp:     Usenet newsgroups

  imap:     accessing mailbox
  pop:      accessing mailbox

  sip:      voice over IP (VoIP)
  sips:     secure voice over IP (VoIP)
  h323:     telephony/videoconferencing (H.323)

  ldap:     directory request
  telnet:   run applications on server

  nfs:      network file system
  wais:     WAIS server
  gopher:   Gopher server

  file:     local files on the host