A megapixel is made up of one million individual pixels. The more megapixels that a camera has, the more sharp the photograph captured will appear. High resolution images means that the amount of megapixels is higher than on a low resolution image.
Pixels are tiny squares that, when viewed as a whole, make up one whole photograph. The megapixels of cameras are measured by the square inch. This means that a camera with 3.5 megapixels (also written as 3.5MP) contains three and a half million pixels in every square inch of photo space. Whether you need a high-megapixel camera depends on the size at which you plan to print your photos. Larger prints require more megapixels to ensure a high enough resolution. Products like digital cameras provide more megapixels than ever before, creating high resolution photographs.