Telecommunications involves the digital transmission of data and voice communications using computers, terminals, communication processors, and software. Signals can be analog, representing continuous waveforms, or digital using discrete 1s and 0s. Modems translate between digital and analog signals. Network topologies include star, bus, and ring configurations. Communications networks span large distances using various cable, satellite, and microwave technologies to connect local area networks (LANs) and wide area networks (WANs). Electronic business technologies enable e-commerce through email, groupware, voice mail, fax, teleconferencing, video conferencing, and distance/e-learning. Electronic data interchange directly exchanges standard business documents between organizations' computers.