All kinds of digital cameras and smartphones are capable of capturing images and saving them in pixels. A Megapixel is one million pixels, which together form a digital image. The greater the number of pixels and consequently the greater the number of Megapixels the higher the resolution of the picture. This is also directly related to the quality of the image.
Of course, Megapixels aren't the only element that determines the quality of an image. Therefore, the Camera that has the highest number of Megapixels isn't always the one taking the most impressive images.