Computer data architecture is based on the binary system of using ones and zeros in a string of eight "bits" to form different characters. Each string of eight bits is called a byte. 8 bits = 1 byte = 1 character as described by the order of the 8 bits of data
For example, the capital letter "K" is expressed in binary bits as "01001011." In traditional usage, 1,024 bits of data equals a kilobit, while 1,024 bytes equals a kilobyte. Kbps always refers to kilobits, while the designation of KB/sec refers to kilobytes.
1024 bits = 1 kilobit
1024 bytes = 1 kilobyte = 8 kilobits
1024 kilobytes = 1 megabyte = 8,192 kilobits
Although these figures are still used in many applications, the International System of Units (SI) provides a slightly different official definition. In order to make the prefixes align with those used in the metric system, they define 1 kilobit as 1,000 bits; 1,024 bits is called a kibibit. The traditional measurements are still most commonly used for computer memory, whereas most networking applications use the SI measurements.
One of the most ubiquitous devices to rate data transfer speeds in terms of kilobits per second is the standard dial-up modem. At 56 kbps it provides the least expensive, albeit the slowest, method of connectivity to the Internet. As an example, DSL modems deliver speeds starting at 144 kbps and ranging upwards of 3,000 kbps, sometimes expressed as 3.0 mbps (megabits per second).
Many high-speed ISPs (Internet Service Providers) continue to describe their services in terms of kilobits, rather than using kilobytes or megabits. This makes it easy for potential customers to compare transfer rates against their existing dial-up modems. When rates are expressed in units other than kbps, it can be confusing to the dial-up shopper.
While a dial-up modem is capable of speeds close to 56 kilobits per second, line noise, network traffic and other interference can cut data transfer speed significantly. Under the best circumstances, a 56 kbps modem will generally operate at about 53 kbps or 6 KB/sec. Here are some conversions that might help when looking at high-speed services:
High-speed services might include DSL, cable and satellite. VDSL (Very high-speed Digital Subscriber Line) can deliver speeds of up to 100 mbps. Generally, the faster the transfer speed, the higher the monthly charge. Household consumers switching from dial-up modems to high-speed access will likely call upon the services of a company providing speeds in the ranges listed above.
With the emphasis on Internet connectivity in work, schools and the home -- and the growing applications requiring higher throughput -- understanding kbps will no doubt become handy in determining the best value for your money when switching ISPs.