As light enters the digital camera lens, it strikes the image sensor. The image sensor then converts the light to electrical charges, which eventually become the pixels that make up the photo.
CCD and CMOS are the two types of image sensor technologies found in a digital camera. CMOS is becoming the more popular type of technology because of its low power consumption and speed.
The number of pixels an image sensor contains determines the resolution of the digital camera. By multiplying the number of pixels the image sensor contains horizontally and vertically, you can determine the maximum resolution of the image sensor, listed in megapixels (MP).