Multimedia artists design computer-delivered electronic systems that allow the user to control, combine, and manipulate different types of media, such as text, sound, video, computer graphics, and animation. The most common multimedia machine consists of a personal computer with a sound card, modem, digital speaker unit, and CD-ROM. Interactive multimedia systems under commercial development include cable television services with computer interfaces that enable viewers to interact with TV programs; high-speed interactive audiovisual communications systems, including video game consoles, that rely on digital data from fibre-optic lines or digitized wireless transmission; and virtual reality systems that create small-scale artificial sensory environments.