A belt is used to tansmit a rotary motion between two or more wheels, like in pulleys or in bikes. Like in gears, a belt join a big wheel and a small wheel. The belt makes the wheels do an anticlockwise motion, but if you can modify this motion so a wheel makes a clockwise one, you've to cross the belt. The belt system is used to move medium forces. Here I leave you an animation of how the belt work.
Well, this is a topic that many young people like: the videogames, so always the people want to buy videogames, first of all they have to choose which console is the best for them. Last year, in November 2013, "Microsoft" left the new generation console, the Xbox One, but then, "SONY", didn't stay back. They left the waited PS4 or Playstation 4, the rival of Xbox One and the best sold in the market. So if you don't have bought anyone and you want to buy them, see this comparative between them so you can choose one. Remember that you can choose the best, but maybe your friends choose the another, so you cannot play with them.
A gear is a mechanism which is used to give power from a component to another one inside a machine. It's formed by a driver wheel, which normally is the smallest, and it's the fastest, and a higher wheel, that moves when the small one moves and it's the slowest. They make a big force with the "teeth" and they do a clockwise motion, but if you wanna change that, you can put another gear in the middle, which is called the "idler" and makes an anticlockwise motion. Here I leave you how do they work.