Stands for "Integrated Services Digital Network." No, it's not the same thing as the ISBN you see in books. ISDN is a data transfer technology, created in 1984, that can transfer data significantly faster than a dial-up modem. ISDN enables wide-bandwidth digital transmission over the public telephone network, which means more data can be sent at one time. A typical ISDN connection can support transfer rates of 64K or 128K of data per second. While these speeds are faster than what you can get with a dial-up modem, the newer DSL technology can support even faster transfer rates and is less costly to set up and maintain.