Videotape is magnetic tape used for storing motion images and usually sound, as opposed to film or random-access digital media. Videotapes are also used for storing scientific or medical data, such as the data produced by an electrocardiogram. In most cases, a helical-scan video head rotates against the moving tape to record the data in two dimensions, because video signals have a very high bandwidth, and static heads would require extremely high tape speeds. Videotape is used in both video tape recorders (VTRs) or, more commonly and more recently, videocassette recorders (VCRs) and camcorders. Tape is a linear method of storing information, and since nearly all video recordings made nowadays are recorded to random-access media such as a hard disk or flash storage, videotape is expected to gradually lose importance as nonlinear/random-access methods of storing digital video data become more common.