A network access point (NAP) is an antiquated term that referred to the original four crossover points that were defined in the United States National Information Infrastructure (NII). These points were used to provide locations for different network service providers (NSPs) to exchange information. These points were later replaced by Internet exchange points (IXPs).
The origins of the Internet as a government-funded academic experiment required a strategy for transitioning to a commercially driven Internet. The development of the network access point system allowed for companies to begin taking over in the development of the Internet. These exchange points were necessary for users of one service provider to access a website stored on another service provider's system.
The network access point system originally had four NAPs, located in Chicago, New Jersey, San Francisco, and Washington, D.C. The network access point system was developed by the National Science Foundation (NSF). This system was set to replace the National Science Foundation Network (NSFNet).
The transition from the government-backed NSFNet to the modern Internet was successful thanks to the series of network access points. These points allowed a relatively simple way for new network service providers to tie in their networks to other networks. This series of interconnected networks is what led to the formation of the Internet as it is known today.
Without the development of the network access point system, it would have been difficult and prohibitively expensive for a single corporation to create the infrastructure necessary for the Internet to exist. The network access point system allowed many different corporations to bind their networks together. This helped to not only reduce the cost of forming the Internet but also helped to encourage competition between the companies. This type of competition helped prevent the development of a monopoly over the entire Internet.
While network access point refers to the four original crossover points that existed in the early days of the Internet, this term is also used by many as being synonymous with Internet exchange points. In general, Internet exchange points serve the same purpose that the original four NAPs served. This is why many individuals use the term synonymously with IXP.