NTSC vs PAL
The broadcast formats for videos meant for home viewing are different in America and the rest of the world. So, while the United States uses the National Television Standards Committe (NTSC) format, European and Asian countries, along with Australia, use the Phase Alternating Line (PAL) format.
The difference is based on the electricla power systems used in different areas for transmission. In America and countries using the NTSC signal, electrical power is generated at 60 hertz so the NTSC signal is transmitted at 60 pulses per second. The PAL electrical pulses go out at 50 pulses per second.
Usually, televisions use a form of an interlacing system that shows 30 alternating lines (in NTSC format) and 25 alternating lines (in PAL format) per second. Based on how fast our eyes put together pictures, these lines appear as a complete moving picture on the screen. Therefore, if a PAL movie is to be transferred to the NTSC format, five frames have to be added to the format.
Another difference between the two formats is their resolution quality. While PAL television broadcasts include 625 lines of resolution, NTSC has 525. More lines signify a greater visual info bank. This is also why when an NTSC videotape is reformatted into the PAL type, black bars cover the top and bottom of the screen.
The NTSC format became prevalent in 1941 and there was not much scope for color transmissions. The PAL system was adopted after the introduction of color broadcasting and effort was made to make the screen picture more closer to the original image in context.
However, for most practical reasons, the difference between NTSC and PAL signals are of little consequences. But, a European television set is not functional in the United States and an NTSC DVD cannot play on a PAL system. The difference between the two technologies has brought business for several companies offering conversions of videos from one format to another.