Pixels and Pixel Per Inch

 
A Pixel (short for “Picture Element”) is the smallest unit of a digital image.
  • If you zoom into a photo far enough, you will see it is made up of a grid of thousands of tiny, coloured squares. Each square is one pixel.
  • An image with a dimension of 1000 x 1000 pixels contains exactly 1 million pixels (1 Megapixel).
 
PPI measures the resolution or “density” of an image. It tells you how many pixels are packed into one linear inch of a screen or printed document.
  • High PPI: Pixels are packed tightly together. The human eye cannot see the individual squares, so the image looks sharp and smooth.
  • Low PPI: Pixels are spread out. The image looks “pixelated” or blocky because the individual squares become visible.