Complementary architecture is when two different types of technology work together to make something better. For example, when you are playing a video game, a programmer might create a game for the Xbox that works together with a headset to make the sound better. The headset acts as a complement to the Xbox, making it better than if you were only playing with the console itself. Another example is when a restaurant has two different food options, one for meat and one for vegetarian customers. The two food options work together to make sure everyone has something they can enjoy eating.