Network Access Point ("NAP") is the original term for the data communications facilities built in the early days of the Internet to provide on-ramp access to higher-speed Internet links (which were typically transcontinental or intercontinental in extent). Also known as Internet Exchange Points ("IXPs"), these facilities in their modern role are an essential component of the global telecommunications and Internet infrastructure. An Internet Exchange Point (IXP for short) is a physical infrastructure that allows different Internet Service Providers (ISPs) to exchange Internet traffic between their networks (autonomous systems) by means of mutual peering agreements, which allow traffic to be exchanged without cost. ...

The National Science Foundation created and supported the first four NAPs - in New York, Washington, D.C., Chicago, and San Francisco - as part of the transition from the original U.S. government-financed Internet to a commercially operated Internet.

An individual network joined the Internet by connecting to the backbone. This backbone was at first the ARPANET. It was later augmented and then replaced by NSFNET, which itself faded away. ARPANET logical map, March 1977. ... National Science Foundation Network (NSFNet) was a major part of early 1990s Internet backbone. ...

Network Access Points originally allowed University networks to join the Internet by connecting to the NSFNET backbone. NAPs were provided at the regional level. A single NAP might serve a geographic area as extensive as a state. More than one region might connect to the backbone network at the same NAP. It was desirable for reasons of network efficiency that traffic heading for the NAP from different University networks be aggregated.

The modern Internet is independent of any single backbone.

In the US, a tier of Internet Service Providers was encouraged to develop between the backbone and the Universities. These Service Provider networks each had a high capacity link to, or a Point of presence at, one or more NAPs. An Internet Service Provider (ISP) is a business or organization that offers users access to the Internet and related services. ... A point-of-presence (POP) is an artificial demarcation or interface point between communications entities. ...