Data Over Cable Service Interface Specification (DOCSIS) is a telecommunications standard used to provide Internet access via a cable modem. It is important because it is a key element in providing modem manufacturers and network service providers (such as Time Warner Cable) a common method for products to work together in a predictable manner.
Like most technical standards, DOCSIS has evolved over time to support new capabilities such as higher Internet service speeds and telephony services. When compared to DOCSIS 2.0, DOCSIS 3.0 is simply a more recent version of the standard.The most visible difference to users is that DOCSIS 3.0 modems provide the highest possible service speeds. That is why Time Warner Cable requires DOCSIS 3.0 modems on its higher speed Internet service tiers.