An Internet service provider (ISP) is an organization that provides access to the Internet. Internet service providers can be either community-owned and non-profit, or privately owned and for-profit. Access ISPs directly connect clients to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and other people. Transit ISPs provide large amounts of bandwidth for connecting hosting ISPs to access ISPs.

Internet connectivity options from end-user to Tier 3/2 ISPs.

The Internet started off as a closed network between government research laboratories and relevant parts of universities. As it became more popular, universities and colleges started giving more of their members access to it. As a result of its popularity, commercial Internet service providers sprang up to offer access to the Internet to anyone willing to pay for the service, mainly to those who missed their university accounts.

Internet service providers in many countries are legally required to allow law enforcement and intelligence agencies to monitor some or all of the information transmitted by the ISP. Modern ISPs integrate a wide array of surveillance and packet sniffing equipment into their networks, which then feeds the data to law-enforcement/intelligence networks and software allowing them to monitor Internet traffic in real time.

An Internet Service Provider is a firm that offers subscribers access to the internet. This internet service provider maintains large runs of cabling and maintains network services in order to transfer and deliver web content to those paying the subscription fee. Typically, these internet service providers focus on DSL, Cable modem, wireless, and more recently, dedicated high-speed interconnects. All in all, there are many different types of Internet Service Providers, and within each and every internet service provider there are often varying levels of service, coverage, as well as personal customer service that comes attached with it. An Internet Service Provider is a complete package of services, which should be researched and considered before an Internet Service Provider is selected.

For most users, the most important qualification is the speed of the connection. Depending on the intended use, there are a myriad of different internet services, and even varying levels of coverage within each and every service. The slowest of these is dial-up internet service. In the early days of internet service, this was typically sufficient, as websites were designed with a lean mentality, with very little imagery and a heavy emphasis on text, and text based linking.

Mid-Range services available for home include Cable Internet or Digital Subscriber Line (DSL) service. For most people, this is sufficient however there are currently faster services available to those who either desire them, or require them to operate their business.

For those simply not interested in paying for internet access, there are a very small number of Free ISPs available. These providers provide internet service free of charge, typically funded through advertising revenue. Netzero, one the earliest example of this service no longer provides an ad supported internet service, and instead focuses on low priced services such as dial up.

All in all, an Internet Service Provider has the very complicated job of setting up and maintaining a network to connect its users to the internet. The inner workings of an ISP vary significantly from company to company, and much of their inner workings are company secret. It's difficult to understand just how internet service providers operate, however from the buyer's perspective the process of using an ISP are incredibly simple. Once a level of connectivity is decided upon, it's simply up to the buyer to research their alternatives, and determine the best solution for their budget and needs.