C# XNA is an extension off of C# that helps programmers make 3D and 2D games. It was discontinued in 2014, but is still widely used today.
Usage[]
In XNA, there is a Game1 class, which inherits from the Game class. The Game1 class recieves a few methods from Game1: Run, LoadContent, UnloadContent, Update, and Draw, just to name a few.
Run[]
The Run method will start the game. This will call LoadContent, and call Update and Draw every 1/60 of a second.
LoadContent[]
This method is used to instantiate most of the objects in the Game1 class. The Game1 Content property allows for loading files in the project, like inages and audio.
Update[]
This is where all the game logic occurs. All object interaction and handling is done here.
Draw[]
The Draw method is where the objects are drawn on-screen, using a SpriteBatch.