Frames per second (frames per second – fps, frame rate)
Imagine a camera that takes several photographs in 1 second. The video or the recording may seem like a moving picture by displaying still images at a specific frame rate. The number of images per second is a frame rate and is measured in frames per second (fps). The higher the number of frames per second the better quality and more smooth is the image displayed by the device. However, the more frames per second the more space is required on the data medium.
The previous systems were based on electric parameters to prevent interferences in the image due to mismatch. NTSC system uses 30 fps (replaced by 29.97 fps in colour TV) determined by 60 Hz mains frequency used in the US, while PAL uses 25 fps also determined by 50 Hz mains frequency used in Europe.