The Senate is considered a continuous body, largely because of the structure of staggered elections. That means, unlike the House, the Senate’s rules persist across sessions. However, that is not to say that the structure of the Senate is immutable. In political science, we think of institutions as the rules, both written and unwritten, that structure the operations of a political body. One analogy I always draw is with the instructions on a board game. When playing any board game, you have a goal, or win condition, determined by the game. The rules of the game then structure your behavior in your path toward that goal. Knowing the rules can change your behavior and alter your decision-making as a rational actor within a fixed institutional context.