Stands for "Network Service Provider." An NSP is a business that provides access to the Internet backbone. While some ISPs also serve as NSPs, in most cases, NSPs provide Internet connectivity to ISPs, which in turn provide Internet access to customers.
NSPs build and maintain the primary infrastructure of the Internet. This includes fiber optic lines between hubs or "Internet exchanges" that route Internet traffic around the world. These communication lines offer extremely high bandwidth of hundreds or even thousands of gigabits per second. The global network created by multiple NSPs enables data to flow seamlessly between computer systems around the world.
In the United States, most NSPs are commercial entities, such as AT&T, Verizon, and MCI. In other countries, NSPs are often owned and operated by the government, though some international NSPs are privately owned as well. While NSPs and ISPs are usually separate companies in the United States, in other parts of the world, they are commonly a single entity. Examples include Tele2 in Europe, and Tata Communications in India.