FPS is an acronym for Frames per Second. It is the unit of measurement for the “frame rate” of a video. When you encode your video for streaming, frame rate is generally one of the settings you can change. Common options are 15 fps, 24 fps, 25 fps, 30 fps and 60 fps. Note 30 fps is commonly used to refer to an actual fps of 29.97.
The higher the fps number, the more images appear every second of video. If you have very detailed video or fast action, then a higher number is necessary to make it appear smooth. An action filled car chase encoded at a low frame rate would appear choppy and unpleasant to watch because parts of the action would appear to be missing.
Low fps is acceptable for screen captures (unless the display has lots of action) and scenes where things are moving at a regular or slow speed. A video of someone sitting on a park bench watching the grass grow wouldn’t need very many frames. If someone walked through the park, or pigeons flew through the scene then a standard 24 or 25 fps would acceptable.
It’s important to know the differences in fps because of the bandwidth each of them use. A PowerPoint presentation recorded on a screen at 15 fps will use approximately one quarter the bandwidth of the same presentation encoded at 60 fps. That’s because each second has four times as many frames in the 60 version. More frames equate to more data, which requires more bandwidth. Note that the relationship between fps and bandwidth isn’t always linear. This example was just for illustration of the concept.
The following is most often recommended to achieve HD streaming quality (assuming sufficient bandwidth is available): 720p @ 30 fps and “true” HD of 1080p @30 fps. Some streaming services have begun accepting 60 fps video since available bandwidth has increased in recent years. These services often use algorithms to judge whether to send a version of the video with a lower fps when bandwidth might be an issue.