MegaPixels:This is the number of pixels each camera sensor uses to process the camera information. It is essentially the resolution of your camera and how sharp your images can get. And it’s measured in millions and is multiplied by the amount of pixels in rows and columns. For instance, 10 MegaPixels equals 10,000,000 pixels. A pixel is the smallest unit that light is exposed to.
ISO:ISO is the speed of your camera’s light sensitivity at a particular setting. During the film days, this was referred to as ASA and had to do with how fast film soaked up light when you took a picture. The faster the film, the higher the ASA. It also meant, though that the film would be grainier, less sharp. In the digital world, its ISO, and the higher the ISO setting, the faster the light can be imaged. But like film, the faster the light gets imaged, the more noise gets invited to the party.
Aperture: Aperture is the size of the hole that the light travels through on its way to the sensor.
Shutter speed: This is the duration of the light being cast on the sensor as the shutter opens and closes. This is quite literal in digital SLRs, but for point and shoots it’s a time value for imaging the light as point and shoots don’t have literal shutters.
CCD: CCD stands for “Charged Coupling Device” and is the sensor that point and shoot cameras use to capture the image in the camera. It then processes it. CCDs tend to be VERY small, about the size of your fingernail and as such, can cause a lot of noise if stuffed with too many megapixels. But they are ideal for the compact nature of point and shoot cameras.
CMOS: CMOS stands for “Complementary Metal-oxide Semiconductor.” This sensor design is primarily used by digital SLRS and can be as large as a full frame 35mm negative. The benefits to CMOS sensors are obvious – greater size equals more light captured for the image and greater resolution. The downside has been that when shooting moving video that the image can get a bit skewed, referred to the rolling shutter issue.
Focal Length: Focal Length is essentially the range of your lens. Whether 3x or 35x it is the ability of the camera to zoom from its widest point to its farthest. And the further you can zoom, the slower the lens gets. So it’s important to keep that in mind.
More info about digital cameras here.