1. The numerical difference between the upper and lower frequencies of a band of electromagnetic radiation, especially an assigned range of radio frequencies.
In computers, definition <code>#</code>2 is almost always the definition referred to.
Bandwidth is usually measured in kilobits (1000 bits per second (kbps).
56 kbps modems usually transfer around 4.2 kilobytes per second while ISDN transfers 128 kbps and transfers around 10-12 kilobyte each second. Most broadband services such as Cable and DSL are a minimum of 300 kbps (about 25k per second) but actual transfer rate varies from service to service and on network usage. T1 transfers up to 1 500 kpbs.
Wireless (802.11) connections speeds range from 3 000 kbps up to 54 000 kbps. The internet backbone has high capacity bandwidth. These T3 connections are consistently faster at around 45 000 kbps. Both UltraSCSI and FastEthernet are even quicker at 80 000 kbps and 100 000 kbps.
The extremely fast fiber optic cable (OC-48) can transfer at speeds of 2.4 gigabytes per second or 2400 000 kbps.