A cable modem is used for connecting to the Internet and is much faster than a typical dial-up modem. While a 56K modem can receive data at about 53 Kbps, cable modems support data transfer rates of up to 30 Mbps. That's over 500 times faster. However, most ISPs limit their subscribers' transfer rates to less than 6 Mbps to conserve bandwidth.
Another important way that a cable modem is different than a dial-up modem is that it doesn't connect to a phone line. Instead, the cable modem connects to a local cable TV line, hence the term "cable modem." This allows cable modems to have a continuous connection to the Internet. Therefore, there is no need to dial your ISP every time you want to check your e-mail.
Cable modems, which have a much more complex design than dial-up modems, are usually external devices, but some models can be integrated within a computer. Instead of connecting to a serial port like a external dial-up modem, cable modems attach to a standard Ethernet port so they can transfer data at the fastest speed possible.