A digital camera's resolution, which is a gauge of how much information and detail a camera can capture, is measured in megapixels. A megapixel if comprised of 2^20 (1,048,576) pixels. This number seems "broken" but in fact it is "rounded" because digital systems are based on binary numbers, which uses base 2 numbers (i.e. 0's and 1's) not base 10 (the numbers that we humans use). Some people round 1 megapixel to 1 million pixels, but the result will be technically wrong. In fact, some manufacturers lie about the true resolution of their digital cameras by assuming that 1 megapixel is 1 million pixels and not 1,048,576 pixels.

In digital imaging, a pixel (picture element) is the basic unit of an image. Pixels are also used to express the resolution of digital displays and pages printed by digital printers. You can think of pixels as a cluster of colored dots that combine to form images in a digital camera, on the computer screen or on a printed page.

A digital camera captures the image with its image sensor and records it on internal storage or, more commonly, on media cards. This image is essentially made up of digital pixels. Pixels are arranged in a grid. They are counted horizontally and vertically. There are more pixels horizontally because the images are wider than they are tall. For example, a 3 MP picture is a 2,048 x 1,536 image. 

So there are two ways for you to represent the resolution of an image. You can say the number of pixels it has on its horizontal axis and on its vertical axis (e.g. 2,048 x 1,536) or you can say the total number of pixels the image has (e.g. 3 megapixels). In summary the number of megapixel of an image is the number of pixels ("colored dots") it has.

The more megapixels a camera can handle, the greater the amount of information it records. Theoretically, the more pixels that the camera has, the greater the image resolution and therefore the higher the image quality and the sharper the pictures. This is why everyone thinks that the number of megapixels is so important. Yet, as we will see further in this article, this is not always true.