1080p refers to the full high definition resolution. The number 1080 means there are 1080 lines of color going from left to right in each picture on the screen. The p means progressive scan (every picture has all the lines every time). 1080p is mostly a 1920x1080p (16:9) widescreen image, but a 1440x1080p (4:3) narrow image is also a full high definition resolution.
