Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. An ISP has the equipment and the telecommunication line access required to have a point of presence on the internet for the geographic area served.

ISPs make it possible for their customers to surf the web, shop online, conduct business, and connect with family and friends—all for a fee. An ISP typically serves as the access point or the gateway that provides a user access to everything available on the Internet.

In 1989 first Internet service provider companies offered the public direct access to the Internet for a monthly fee, were established in Australia and the United States.These companies generally offered dial-up connections, using the public telephone network to provide last-mile connections to their customers.

Working Of ISP: ISPs are connected to one or more high-speed internet lines. Larger ISPs have their own high-speed leased lines, so they are less dependent on telecommunications services and can provide better service to their customers.Multiple ISPs are connected to large backbone routing centers.

ISPs are categorised into three tiers:

• Tier 1 ISPs: Tier 1 ISPs have the most global reach and own enough physical network lines to carry most traffic on their own. They also negotiate with other tier 1 networks to allow free traffic to pass through between other tier 1 providers. Tier 1 ISPs typically sell network access to tier 2 ISPs. Tier 1 ISPs continue to invest in infrastructure and they may well be the only players in the market until new technologies that don't depend on fiber in the ground emerge.

• Tier 2 ISPs: Tier 2 networks focus on consumer and commercial customers. These ISPs have regional or national reach and are service providers that connect tier 1 and tier 3 ISPs. They have to purchase access to larger tier 1 networks, but are peers with other tier 2 ISPs.

• Tier 3 ISPs: These ISPs connect customers to the internet using another ISP's network. These ISPs use and pay higher-tier ISPs for access to internet services. They focus on providing internet access to local businesses and consumer markets.