When you define a class then you define a blueprint for a data type. A class describes these things like data such as fields, methods, properties, members, and events in to a single unit. And in most cases, when you create an instance of that class, now referred to as an object. The class is actually a group of similar objects and logical data.
Let's see an example of C# class that has two fields only.
public class Student
int id;//field or data member
String name;//field or data member