What are pixels? The word “pixel” means a picture element. Every photograph, in digital form, is made up of pixels. They are the smallest unit of information that makes up a picture. Usually round or square, they are typically arranged in a 2-dimensional grid.
In the image below, one portion has been magnified many times over so that you can see its individual composition in pixels. As you can see, the pixels approximate the actual image. The more pixels you have, the more closely the image resembles the original.
The number of pixels in an image is sometimes called the resolution, even though this is a bit of a misuse of the term. If we are using the term to describe pixel count, one convention is to express resolution as the width by the height, for example a monitor resolution of 1280×1024. This means there are 1280 pixels from one side to the other, and 1024 from top to bottom.
Another convention is to express the number of pixels as a single number, like a 5 megapixel camera (a megapixel is a million pixels). This means the pixels along the width multiplied by the pixels along the height of the image taken by the camera equals 3 million pixels. In the case of our 1280×1024 monitors, it could also be expressed as 1280 x 1024 = 1,310,720, or 1.31 megapixels.