The multipoint control unit (or MCU) is a device present in all multipoint videoconferencing systems and is essential to how multipoint videoconferencing functions. The MCU allows for three or more separate locations to conduct a real time videoconference. MCUs consist of either a sole piece of software or a combination of both hardware and software, and come in variations specifically dedicated to IP or ISDN videoconferencing. A multipoint control unit is located at the end of a Local Area Network (LAN) and is composed of a multipoint processors (MPs) and a multipoint controller (MC). The MCU acts as a bridge to unite three or more sources to partake in a multipoint videoconference. The more expensive multipoint control units are capable of handling more connections at a faster data transfer rate and allow for more than one participant to be displayed on the video screen at one time.