How it affects your pictures
Pixels are like dollars. Unless you’re applying for a college loan, the more you have the better. For you, more megapixels means more versatility and more creativity. You can make bigger prints and can crop your pictures more to zoom in on a face, a barn, a boat, or whatever you’d like to enlarge. With a 5- or 6-megapixel camera, you can even crop creatively to make several pictures out of one. And you can effectively use that digital zoom.
How it affects print size
Take pictures with a 4-megapixel or larger camera and you can create inspiring poster prints of your favorite shots. Or zoom way in and crop your pictures and still make 5x7-inch and 8x10-inch prints. But if you take only snapshots, a 2- to 3-megapixel camera should be fine for standard 4x6-inch prints and small enlargements.