Prestel
In 1983, the Prestel messaging service known as “Prestel Mailbox” was launched, initially hosted on the computer known as "Enterprise", and later available from all IRC computers by means of a centralised messaging computer known as "Pandora". This facility extended the original day one concept of “Response Frames” whereby an end user could send a message back to the IP who owned the page via special pages, for example to order goods or services. The user’s name, address, telephone number, and date could be added automatically to the message when the IP set up the response frame by means of codes which triggered extraction of key data from the users account held on the IRC computer. Initially response frames were ingathered by an IP from each IRC individually, but later the facility to collect messages from all IRCs at the UDC from where they could be ingathered centrally was implemented, and with the introduction of Mailbox, they could be retrieved from any IRC.
History of the Internet
Stemming from the first specifications of TCP in 1974, TCP/IP emerged in mid-late 1978 in nearly its final form, as used for the first decades of the Internet, known as "IPv4". which is described in IETF publication RFC 791 (September 1981).
IPv4 uses 32-bit addresses which limits the address space to 2 addresses, i.e. addresses. The last available IPv4 address was assigned in January 2011. IPv4 is being replaced by its successor, called "IPv6", which uses 128 bit addresses, providing 2 addresses, i.e. . This is a vastly increased address space. The shift to IPv6 is expected to take many years, decades, or perhaps longer, to complete, since there were four billion machines with IPv4 when the shift began.