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Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion. A video camera is a camera used for electronic motion picture acquisition, initially developed by the television industry but now common in other applications as well. The earliest video cameras were those of John Logie Baird, based on the electromechanical Nipkow disk and used by the BBC in experimental broadcasts through the 1930s. All-electronic designs based on the cathode ray tube, such as Vladimir Zworykin’s Iconoscope and Philo T. Farnsworth’s Image dissector, supplanted the Baird system by the 1940s and remained in wide use until the 1980s, when cameras based on solid-state image sensors such as CCDs (and later CMOS active pixel sensors) eliminated common problems with tube technologies such as burn-in and made digital video workflow practical. Video cameras are used primarily in two modes. The first, characteristic of much early television, is what might be called a live broadcast, where the camera feeds real time images directly to a screen for immediate observation. A few cameras still serve live television production, but most live connections are for security, military/tactical, and industrial operations where surreptitious or remote viewing is required. The second is to have the images recorded to a storage device for archiving or further processing; for many years, videotape was the primary format used for this purpose, but optical disc media, hard disk, and flash memory are all increasingly used. Recorded video is used in television and film production, and more often surveillance and monitoring tasks where unattended recording of a situation is required for later analysis. Modern video cameras have numerous designs and uses, not all of which resemble the early television cameras.
A Sony high definition video camera. A videotape is a recording of images and sounds on to magnetic tape as opposed to movie 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, video cassette recorders (VCRs) and video cameras. Tape is a linear method of storing information and, since nearly all video recordings made nowadays are digital, it is expected to gradually lose importance as non-linear/random-access methods of storing digital video data become more common. 
An assortment of video tapes 
A reel of 2-inch quad videotape compared with a modern-day miniDV videocassette 
Bottom view of VHS videotape cassette with magnetic tape exposed
DV cassettes Left to right: DVCAM-L, DVCPRO-M, DVC/MiniDV Methods and media for sound recording are varied and have undergone significant changes between the first time sound was actually recorded for later playback until now. Digital recording and reproduction converts the analog sound signal picked up by the microphone to a digital form by a process of digitization, allowing it to be stored and transmitted by a wider variety of media. Digital recording stores audio as a series of binary numbers representing samples of the amplitude of the audio signal at equal time intervals, at a sample rate so fast that the human ear perceives the result as continuous sound. Digital recordings are considered higher quality than analog recordings not necessarily because they have higher fidelity (wider frequency response or dynamic range), but because the digital format can prevent much loss of quality found in analog recording due to noise and electromagnetic interference in playback, and mechanical deterioration or damage to the storage medium. A digital audio signal must be reconverted to analog form during playback before it is applied to a loudspeaker or earphones. the phonograph expanded on the principles of the phonoautograph. Perfected by Thomas Edison in 1878, the phonograph was a device with a cylinder covered with an impressionable material such as tin foil, lead, or wax on which a stylus etched grooves. The depth of the grooves made by the stylus corresponded to change in air pressure created by the original sound. The recording could be played back by tracing a needle through the groove and amplifying, through mechanical means, the resulting vibrations. A disadvantage of the early phonographs was the difficulty of reproducing the phonograph cylinders in mass production. 
Edison’s cylinder-based Phonograph This changed with the advent of the gramophone (phonograph in American English), which was patented by Emile Berliner in 1887. The gramophone imprinted grooves on the flat side of a disc rather than the outside of a cylinder. Instead of recording by varying the depth of the groove (vertically), as with the phonograph, the vibration of the recording stylus was across the width of the track ( horizontally). The depth of the groove remained constant. Berliner called this audio disc a "gramophone record", although it was often called a "phonograph record" in U.S. English. Early disc recordings and phonograph cylinders had about the same audio fidelity (despite the cylinder’s theoretical advantages of constant linear groove speed and greater dynamic range of the hill-and-dale groove geometry). However, disc records were easier and cheaper to mass produce. From the beginning, the flat disks were easily mass-produced by a direct molding process, pressing a master image on a plate of shellac. 
The disk-based gramophone 
7" reel of ¼" recording tape, typical of audiophile, consumer and educational use in the 1950s–60s 
audio cassette 
The DAT or Digital Audio Tape
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