Our game will now enter an endless loop in which the Update() and Draw() methods are called repeatedly until we exit the application. By default, this loop attempts to run 60 times per second on the Windows and Xbox platforms, and 30 times per second on the Windows Phone platform.
The Update() method is used to process all of our game logic, such as checking for and reacting to player input, updating the positions of objects in the game world, and detecting collisions. The Update() method has a single parameter, gameTime, which identifies how much real time has passed since the last call to Update(). We can use this to scale movements smoothly over time to reduce stuttering that would occur if we make the assumption that our update will always run at a consistent frame rate, and code on other system events impacted by the update cycle.