A Data Over Cable Service Interface Specification or DOCSIS modem is a device that consumers use to transfer data over cable TV networks. As of July 2015, the fastest DOCSIS modem on the market is the DOCSIS 3.1 modem; DOCSIS 4.0 modems are not available yet.
The latest DOCSIS 3.1 technology is capable of up to 10-Gigabytes per second downstream speeds. A consumer’s active link speeds, however, depend on his cable broadband service provider’s capabilities. As of July 2015, the current market has three DOCSIS modem specification levels: 1.x, 2.x and 3.x. Each iterative layer is better than its predecessor. For example, the 3.x specification level is superior to 1.x specification level.