http://www.digicamhelp.com/camera-features/camera-parts/megapixels/
"Digital cameras capture images as pixel elements, known as pixels. Simply put, a megapixel is equal to one million pixels.
Digital images are made up of thousands of these tiny, tile-like picture elements. The more pixels, the higher the image resolution.
Resolution relates primarily to print size and the amount of detail an image has when viewed on a computer monitor at 100%.
Elements of picture quality
The number of megapixels is only one aspect relating to the quality of a camera, or the actual quality of a photo it is capable of producing. Factors such as camera sensor and processor, and the optical quality of a lens, play equally important roles"
I have to explain this every time. It's like it never sticks to any of these dudes brains.