Frames per Second (FPS), also called “frame rate,” is the number of still, distinct images displayed per second to trick our eyes into believing objects are moving.
It is a metric of fluidity.
A normal television show in the States (NTSC TV) is broadcast at 30 FPS (frames per second). PAL TV is 25 FPS. Movies are shown at 24 FPS.
20 FPS are considered by many to be the minimum to trick the eye, and is the minimum to enable the simualtion genre known as practiceware.
Higher frame rates (like 60 FPS) results in more appealing animation, and some console games sacrifice other elements to maintain this level. Fewer FPS are the results of system limitations, poor programming, other applications consuming system resources (such as AI), and detail of image, including screen resolution and complexity of objects, and lighting.