Simple defination of pixel
In digital imaging, a pixel dots or picture element is a physical point in a raster image, a pixel is it is the smallest controllable element of a picture represented on a screen. Each pixel is therefore a sample of an original image. The more samples provided the more accurate representations of the original. In color image systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black.