Hallo! Me again!

Well, is in C# a posibility to define variables global?

For example is something like this possible?

Code:
class proggi
{
   public Connection;
   
   void run()
   {
      A.Init();
      B.Use();
   }
}
class A
{
   public void Init()
   {
      // Initialise Connection in class proggi
   }
}
class B
{
   public void Use()
   {
      // Use Connection in class proggi
   }
}
I know that it is easy, if I "put" the varibale Connection into the Parameter list of Init and Use. But is there a possibility to avoid this?

Thanks for help!

Taggi