Communication · 1974

TCP/IP

Cerf and Kahn design a protocol that lets any network connect to any other.

Vint Cerf and Bob Kahn published the Transmission Control Program design in May 1974, later split into TCP and IP. ARPANET switched to TCP/IP on 1 January 1983, and the protocol's openness let independent networks join into one internet.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 2

ARPANET 1969
Packet switching 1964

What it led to 4

Domain Name System 1983
NSFNET backbone 1986
World Wide Web 1991
Continental quantum networks ~2040

Related measurements

The dashed line marks when it first worked.

Internet users in the United States Latest: 322M people (2024) Source: Our World in Data

Share of people online Latest: 73.6 % (2025) Source: Our World in Data