Resolution, in video, is the width and height of the movie in pixels
The big step in video quality came with the introduction of HD, or High Definition video, and this comes in two resolutions.
Standard HD video measures 1280 pixels wide by 720 pixels high, and while this might not sound much, the persistence of vision effect of moving pictures makes it look sharp and clean, especially when shot with a good camera and played back on a good TV or monitor.
All except the most basic models can now shoot full HD, which has a resolution of 1920 x 1080 pixels. When it's shot and played back with good equipment, this gives more than enough definition for most needs.
There's another big step up which is hitting the market right now. '4K video', as a general term, means video with twice the horizontal resolution of full HD at around 4,000 pixels (hence, '4K'). In fact, the strict definition of 4K video is footage with a resolution of 4,096 x 2,160 pixels, whereas makers usually mean a slightly lower 'UHD' resolution, but the difference is scarcely worth worrying about.
4K is not the highest resolution available. Pro camera maker Red, for example, is already selling 6K and 8K cameras.
