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ISP (internet service provider)

What is an ISP?

An ISP (internet service provider) is a company that provides individuals and organizations access to the internet and other related services. 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 customers to access the internet while also providing additional services such as email, domain registration and web hosting. ISPs may also provide different internet connection types, such as cable and fiber. Connections can also come in the form of high-speed broadband or non-broadband. The Federal Communications Commission (FCC) states that to be considered high-speed, a connection must have download speeds of at least 25 megabits per second (Mbps) and upload speeds a minimum of 3 Mbps.

An ISP is also sometimes referred to as an internet access provider. ISP is also sometimes used as an abbreviation for independent service provider to distinguish a service provider that is a separate company from a telephone company.

How do ISPs work?

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.

ISPs also keep thousands of servers in data centers -- the number of servers depends on their internet service area. These large data centers manage all customer traffic. Multiple ISPs are also connected to large backbone routing centers.

ISPs are grouped into the following three tiers:

  • Tier 1 ISPs. These 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 to other tier 1 providers. Tier 1 ISPs typically sell network access to tier 2 ISPs.
  • Tier 2 ISPs. 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 2 networks focus on consumer and commercial customers.
  • Tier 3 ISPs. These ISPs connect customers to the internet using another ISP's network. Tier 3 ISPs use and pay higher-tier ISPs for access to internet services. They focus on providing internet access to local businesses and consumer markets.

ISPs and the different types of services

ISPs provide the following internet services:

  • Cable. This service uses coaxial cable -- the same type of cable that delivers TV. Cable internet has low latency, which is good for users who need less delay or lag time. Cable has a download speed of 10 to 500 Mbps and an upload speed of 5 to 50 Mbps.
  • Fiber. Fiber internet uses fiber optic cable to transmit data to provide much faster speeds compared with cable or digital subscriber line (DSL). Fiber has download speeds of 250 to 1,000 Mbps and upload speeds of 250 to 1,000 Mbps. Fiber is good for online gamers and other heavy internet users.
  • DSL. DSL connects users to the internet using a telephone line. It is widely available, but is slowly being replaced by more reliable broadband connections such as cable and fiber. DSL is slower and offers download speeds of 5 to 35 Mbps and upload speeds of 1 to 10 Mbps. It is a good option for users in rural areas and those who mainly surf the web or stream TV on only one device.
  • Satellite. Satellite internet access works through the use of communication satellites. Ground stations relay internet data as radio waves to and from satellites that are likely in low Earth orbit and to farther ground stations. Satellite is slower, with download speeds of 12 to 100 Mbps and upload speeds of 3 Mbps, but it is a good option for users in remote areas.

Most ISPs offer a combination of these services.

What are examples of ISPs?

According to independent research by BroadbandNow and data from the FCC, there are more than 2,900 ISPs in the U.S. These ISPs offer a variety of services. The top five ISPs by estimated population covered include HughesNet, Viasat Internet, AT&T Wireless, Verizon and T-Mobile.

To break this down based on the tiers examined above, tier 1 ISPs include the following U.S.-based companies:

  • AT&T
  • CenturyLink
  • Sprint
  • Verizon

Tier 2 ISPs include the following companies:

  • Comcast
  • Cox Communications
  • CTS Telecom

Tier 3 ISPs include smaller regional and local providers.

How to choose an ISP

Users should choose an ISP based on several factors, including the following:

  • Coverage area. Which providers offer service to the user's region? If the user lives in a rural area, there may be limited options.
  • Types of services offered. In addition to cable, fiber, DSL or satellite, does the ISP offer online security? Free email access? Hosting for websites? What about mesh Wi-Fi? Be sure the ISP's offerings match the user's needs.
  • Download and upload speeds. Will the user be gaming online or working from home and using video teleconferencing? Both require different levels of service. For example, at least 25 Mbps of bandwidth is needed to stream 4K video.
  • Pricing. Does the ISP bundle services such as internet, phone and TV, and if so, does combining services save money? Are there any data caps? What about equipment costs? Is there a contract?
  • Consumer satisfaction rating. Check unbiased sources for provider ratings.
Chart showing different bandwidth requirements
Bandwidth requirements for various multimedia and voice functions.

ISPs may throttle, or slow down, a user's internet speed in order to regulate traffic and clear up network congestion. ISPs may also throttle a user's internet speed when the user reaches a specific data limit. However, throttling violates the idea of net neutrality, which is the prevailing thought that ISPs should give equal treatment to all communications over the internet.

As an example, ISPs can choose to throttle specific websites that users visit simply because they take up a lot of data. ISPs have, in the past, throttled their customers' internet when connecting to Netflix -- meaning the user experience on Netflix's platform is diminished due to the ISP.

Learn about potential speed inequalities with broadband, such as the projected internet speeds in different locations in the future.

This was last updated in February 2022

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