A megapixel refers to one million pixels, and is used as an indication of resolution capability for digicams.
Digicams with large sensors and high-quality lenses take crisp and sharp shots.
It helps in getting ‘close’ to your subject or magnifies it.
Shutter lag and startup time:
The delay between triggering the shutter and when the photo is actually taken is the shutter lag. Before buying a camera, check how long it takes to take its first shot. If it takes a second or less, you have a fast camera.
—As told by A. Rajkumar, Fujifilm India