1080p is the shorthand name for a category of video modes. The number 1080 represents 1,080 lines of vertical resolution[1], while the letter p stands for progressive scan or non-interlaced. 1080p is considered an HDTV video mode. The term usually assumes a widescreen aspect ratio of 16:9, implying a horizontal (display) resolution of 1920 dots across and a frame resolution of 1920 1080 or over two million pixels. The frame rate in hertz can be either implied by the context or specified after the letter p (such as 1080p30, meaning 30 frames per second).
http://en.wikipedia.org/wiki/1080p