ADSL stands for Asymmetric (or Asynchronous) Digital Subscriber Line. It is a type of high-speed Internet service provided over copper telephone lines that coexists with regular telephone service. That is, one can use the telephone and surf the Internet simultaneously. An ADSL router is a piece of networking equipment that allows the Internet account to be shared by several computers in the same location. A modem is also required, but is usually built into the router. An ADSL router can be wired, or wireless.
In networking jargon, whenever one connects two or more computers together that are located in close proximity such as in a house or office building, a local area network (LAN) is created. A router has Ethernet® ports on the back for plugging in each computer. Ethernet® is the type of cable required for creating a wired network, and each computer must also have an Ethernet® networking card installed, which provides its own port. Ethernet® cable is then run between each computer and the router. Some routers might also feature USB connectivity.
Alternately, a wireless LAN can be created by using a wireless ADSL router. This type of router communicates with each computer on the LAN through radio waves. In this case a wireless networking card is required in each computer. The router and computer cards must share a common wireless protocol or language to "hear" each other. These standards are always evolving and are designated as 802.11 with a letter following that identifies the exact protocol; such as 802.11g and 802.11n.
A wireless router that only supports 802.11n, for example, will not be able to communicate with a laptop that has a wireless 802.11g card installed, and visa-versa. When a router does not support the type of wireless card installed in a desktop or laptop, an external network adapter can be purchased for that machine that supports the correct protocol. Network adapters are made to use a USB port or an ExpressCard® slot. Some routers support multiple wireless standards, conveniently eliminating the worry as to what type of wireless network cards are installed in the various machines planned for use in the LAN.
Virtually all routers come with a build-in hardware firewall. The router’s firewall is designed to block traffic coming in from the Internet that has not been requested by a machine on the LAN. Wireless routers also come with the ability to encrypt traffic on the LAN to prevent eavesdropping by nosy neighbors or passersby.
Many ISP’s provide an ADSL router with their service that has been preconfigured to work with their network. You can also buy your own router, configuring it for use with the service yourself. Configuration is done through software, where the basic parameters of the connection can be changed to accommodate nearly any ISP. Additionally, advanced users can open ports as required for gaming or for remote desktop applications, to name just two examples. Many other tweaks and options are also available.
For gamers or for fans of Voice over IP (VOIP) services like Skype®, an ADSL router with QoS (Quality of Service) can prioritize applications of choice to ensure smoother game play and reduce delays in conversations. Also, if your ISP offers ADSL2 in your area, (a newer and faster version of ADSL), you will require a router that supports ADSL2. Many routers today support both ADSL and ADSL2, but not all, so look for compatibility before purchasing your router. An ADSL router can cost between $35 - $100 US Dollars (USD) or more, depending on features and supported standards.
