What is the default access for a class member in C#?

The default access for a class member in C# is private.

Member variables i.e. class members are the attributes of an object (from design perspective) and they are kept private to implement encapsulation. These variables can only be accessed using the public member functions.

Example

using System;

namespace RectangleApplication {
   class Rectangle {
      //member variables
      private double length;
      private double width;

      public void Acceptdetails() {
         length = 10;
         width = 14;
      }

      public double GetArea() {
         return length * width;
      }

      public void Display() {
         Console.WriteLine("Length: {0}", length);
         Console.WriteLine("Width: {0}", width);
         Console.WriteLine("Area: {0}", GetArea());
      }
   }//end class Rectangle

   class ExecuteRectangle {
      static void Main(string[] args) {
         Rectangle r = new Rectangle();
         r.Acceptdetails();
         r.Display();
         Console.ReadLine();
      }
   }
}