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Internet access speed is a measurement of how fast data can be transferred from the Internet to a connected computer. Broadband plans are commonly advertised as guaranteeing speeds that fall within a certain range with faster plans priced higher. An exact speed cannot be guaranteed, as many factors can affect it, depending on the technology.
Digital Subscriber Line (DSL) service is provided over standard copper telephone lines. It shares the lines with phone service, allowing both technologies to use the lines at the same time without interference. DSL is brought into a neighborhood by a DSL Access Multiplexor (DSLAM) that acts like a router for the immediate area.
Physical lines feed out from the DSLAM into the community with the length of these lines limited by signal degradation. The farther the signal has to travel from the DSLAM, the more likely to encounter latency issues affecting Internet access speed. A customer who lives close to the DSLAM and subscribes to an entry-level plan that advertises speeds of 500-768 kilobits per second (kbps), will see speeds closer to the higher end of that range than a neighbor who lives near the limit of the DSLAM’s reach.
Cable broadband provides Internet access over the same coaxial cable that brings television to the premises. Cable Internet speed does not fluctuate according to the physical location of its customers, but this technology does assign specified amounts of bandwidth to areas. If many local residents are online at the same time, supply might run short of demand, slowing access for everyone in the area. Cable plans are commonly advertised as having “speeds up to” a certain threshold, allowing for slower speeds.
While entry-level DSL plans start at an affordable 768 kbps, the slowest cable plans are typically 1.5 megabits per second (mbps). There are roughly 1,000 kilobits in 1 megabit, so 1.5 mbps is two-to-three times as fast as the slowest DSL plan and generally costs two-to-three times as much. More often than not, however, cable is not offered in tiered plans like DSL, and a customer must take whatever the local cable provider offers. This might be a much faster plan of 3.0 to 6.0 mbps, at a higher price.
DSL also offers competitive plans in the 3.0 mbps range, depending on the provider. The technology has evolved to be able to offer even faster access, up to 6.0 mbps or more, but very fast DSL is generally priced too high to be competitive in the United States. Fiber optic services offer plans with Internet access speeds up to 50 mpbs, though these extremely fast plans are typically priced quite high. Some Internet service providers that use the technologies of very fast DSL or fiber optic lines sometimes offer plans with throttled down speeds in the 3.0 mbps range to be more affordable.