INTERNET SERVICE PROVIDER:
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.[1] Hosting ISPs lease server space for smaller businesses and other people (colocation). Transit ISPs provide large amounts of bandwidth for connecting hosting ISPs to access ISPs.[2]
Access providers
Main article: Internet
access
ISPs employ a range of technologies to enable consumers to connect to their
network.[citation needed]For users and small businesses, traditional options include: dial-up, DSL (typically Asymmetric Digital Subscriber Line, ADSL), broadband wireless, cable modem, fiber to the premises (FTTH), and Integrated Services Digital Network (ISDN) (typically basic rate interface).[citation needed]
For customers with more demanding requirements, such as medium-to-large businesses, or other ISPs, DSL (often Single-Pair High-speed Digital Subscriber Line or ADSL), Ethernet, Metropolitan Ethernet, Gigabit Ethernet, Frame Relay, ISDN (B.R.I. or P.R.I.), ATM (Asynchronous Transfer Mode) and upload satellite Internet access. Sync-optical cabling (SONET) are more likely to be used.[citation needed]
Many access providers also provide hosting and email services.[citation needed]
Hosting ISPs
Hosting ISPs routinely provide email, FTP, and web-hosting services. Other services include virtual machines, clouds, or entire physical servers where customers can run their own custom software.[citation needed]Transit ISPs
In the simplest case, a single connection is established to an upstream ISP and is used to transmit data to or from areas of the Internet beyond the home network; this mode of interconnection is often cascaded multiple times until reaching a Tier 1 carrier. In reality, the situation is often more complex. ISPs with more than one point of presence (PoP) may have separate connections to an upstream ISP at multiple PoPs, or they may be customers of multiple upstream ISPs and may have connections to each one of them at one or more point of presence.[citation needed]
Virtual ISPs
Main article: Virtual ISP
A Virtual
ISP (VISP) is an operation which purchases services from another ISP
(sometimes called a "wholesale ISP" in this context)[4]
which allow the VISP's customers to access the Internet using services and
infrastructure owned and operated by the wholesale ISP.Free ISPs
Free ISPs are Internet Service Providers (ISPs) which provide service free of charge. Many free ISPs display advertisements while the user is connected; like commercial television, in a sense they are selling the users' attention to the advertiser. Other free ISPs, often called freenets, are run on a nonprofit basis, usually with volunteer staff.[citation needed]Peering
Main article: Peering
ISPs may engage in peering, where multiple ISPs
interconnect at peering points or Internet exchange points
(IXs), allowing routing of data between each network, without charging one
another for the data transmitted—data that would otherwise have passed through
a third upstream ISP, incurring charges from the upstream ISP.[citation needed]ISPs requiring no upstream and having only customers (end customers and/or peer ISPs) are called Tier 1 ISPs.[citation needed]
Network hardware, software and specifications, as well as the expertise of network management personnel are important in ensuring that data follows the most efficient route, and upstream connections work reliably. A tradeoff between cost and efficiency is possible.[citation needed]
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