What does HD, SD, and UHD mean?

These are the resolutions available for Aosu camerasSD stands for Standard Definition (video peaks at 720576 pixels)HD stands for High Definition has a width of 1280 x 720 pixels (1 megapixel)UHD stands for Ultra High Definition also known as 4K and 4K (its resolution is 3840 pixels horizontally by 2160 pixels vertically, which is frequently referred to as 2160p).