I've been asked a number of times if one should purchase a camera with 12 megapixels, 14 megapixels, or if 10 megapixels are enough.
A megapixel is one million pixels. In digital photography, it refers to the number image sensor elements on a digital sensor. For example, an 8 megapixel camera has eight million light-sensitive elements on the sensor.
The more light-sensitive elements that are on the image sensor, the higher the resolution the digital photograph will be. Generally speaking, a camera with 12 megapixels will produce a better looking image than an 8 megapixel camera.
But the answer isn't quite as simple as that.
First, a digital sensor can only hold so many light-sensitive elements. Eventually, you run out of room. Camera companies have thought of a way around this: smaller light-sensitive elements. These smaller elements don't respond to low-light conditions nearly as well as normal elements. They don't translate to actual image resolution in the same way as normal light-sensitive elements, as well.
There are over 50 different sizes of image sensors for digital cameras. It's much better to have 12 regular-sized megapixels on a mid-sized sensor than 12 small-sized megapixels on a small sensor.
In other words, sensor size is just as important as megapixel count, and both work hand-in-hand to produce resolution.
Something else to consider is how the image will be used. Most people don't need more than 6 megapixels. That's plenty for a quality 8" x 10" print after a small amount of cropping. Depending on just how large of prints you want and how much cropping you plan to do, 10 megapixels might be complete overkill. So the question of how many megapixels might be irrelevant to you. 8, 10, 12, 14 megapixels? Who cares?
Well, again, depending on how large of prints or how much cropping one desires, even 14 megapixels might not be enough. Some (but not many) professional photographers need more than 20 megapixels. However, if you had to ask the question in the first place, that's probably not you. And if you do find yourself in that small group of people needing extra-large resolution, I suggest film (35mm or larger) and a high quality scan.
I have a 12.4 megapixel digital camera with a mid-sized sensor, and it produces an image resolution that is plenty large enough for what I need it for. Probably 98% of photographers don't need any more resolution than what that camera produces.
Lens quality and the built-in software to process the data are also important. If those two things are poor than the number of megapixels might not matter much. However, pretty much any digital camera over $150 will at least be adequate in quality.
The conclusion is that if you are stressing out wondering if you should get a 10, 12 or 14 megapixel digital camera--stop! It's not nearly as important as camera companies and camera stores would have you believe. Get the camera that has the best value and don't lose sleep over megapixels.
Besides, your camera doesn't matter, anyway.