Short for 4K resolution (also known as 4K UHD), 4K is a term that stands for a horizontal screen display resolution of 4,000 pixels. When speaking about theater projectors, 4K stands for a horizontal resolution of 4,096 pixels; however, it is also very common to refer to Ultra HD (UHD) TV resolution as to 4K resolution as well (although the exact UHD TV resolution is actually 3,840x2160px, not full 4,000 pixels in width).
