An Internet Service Provider (ISP) is a company or organization that offers services for accessing, using, managing, or participating in the Internet. ISPs can be commercial, community-owned, non-profit, or privately owned entities. The primary service provided by ISPs is Internet access, which can be delivered through various technologies such as dial-up, DSL (Digital Subscriber Line), cable modem, wireless, or fiber-optic connections. In addition to Internet access, ISPs often offer related services including Internet transit, domain name registration, web hosting, and colocation.
ISPs play a crucial role in connecting individuals and organizations to the Internet, enabling the transfer of data across the global network. They maintain the infrastructure necessary for Internet connectivity and manage the flow of Internet traffic. Depending on the technology and infrastructure available, ISPs can provide different levels of Internet connection speeds, from slower dial-up connections to high-speed broadband. The Federal Communications Commission (FCC) defines high-speed broadband as having download speeds of at least 25 megabits per second (Mbps) and upload speeds of at least 3 Mbps.
ISPs are categorized into three tiers based on their reach and the nature of their network connections:
Tier 1 ISPs:
These have the most extensive global reach and own significant portions of the physical network infrastructure. They can carry most of their traffic without needing to pay other ISPs for transit and typically sell network access to Tier 2 ISPs.
Tier 2 ISPs:
These have regional or national reach and act as intermediaries between Tier 1 and
Tier 3 ISPs. They purchase access from Tier 1 networks and may peer with other Tier 2 ISPs.
Tier 3 ISPs:
These ISPs connect end customers to the Internet using the network of higher-tier ISPs. They focus on providing Internet access to local businesses and consumers.
ISPs may also engage in peering arrangements, where they interconnect at peering points or Internet exchange points (IXPs), allowing data to route between each network without incurring charges from upstream ISPs. This practice helps in efficiently managing Internet traffic and reducing the cost of data transit.
In addition to providing Internet access, ISPs are responsible for ensuring the security and reliability of their services. They may offer bundled services, including phone and cable TV, especially when the underlying infrastructure supports multiple services. ISPs also play a role in protecting their subscribers from cyber threats and may have policies in place to manage network congestion and ensure fair use of resources.
Overall, ISPs are essential for facilitating access to the Internet, supporting a wide range of online activities for individuals and organizations worldwide.