Let me add to the good answers you've received already.Gaming mice and keyboards are usually more ergonomic, and have less input lag than a normal device. The input lag is key. With many devices, you click the button, it takes anywhere from 8 to 25/1000 of a second (8 to 25ms) to process it and another 2-3ms to send the response to the computer. Granted, you don't notice the 8ms, and 25ms is probably still unnoticeable, but many a shoot-out in FPS games are won by he/she who has the least video/input device/internet lag. Gaming mice have less input lag (2 to 8ms), and 1ms polling rates (the rate it sends info to the computer)Gaming mice specifically have features that make them better for gaming. They are more precise (the DPI mentioned earlier), have less lag, and include things like weight cartridges and on-the-fly dpi switching. The DPI switching allows you to go from really fast motions to very controlled movements. For example, you might want to run around with an assault rifle in a game, then switch down to a controlled movement for a long-range sniper shot.Gaming keyboards are generally back-lit, and have higher-quality parts. This means they look awesome, have a better feel to the button, and last longer. I'll grant that it doesn't matter as much to most people, but it will matter a lot if you're pressing six buttons at once. For gamers - especially FPS (first-person shooter) gamers, gaming mice are a must-have, and keyboards are just a lot nicer. MMO players will also appreciate gaming mice for having more buttons, which allows them to bind more functions and macros to east-to-press buttons.