What are the classes of the senate?

In the United States Senate, there are three classes of senators, designated as Class I, Class II, and Class III. These classes are used to stagger the election cycles, ensuring that approximately one-third of the Senate is up for re-election every two years. This system helps maintain continuity within the Senate while allowing for periodic renewal of its membership. Each class has senators from various states, with their terms expiring in different years.