The most commonly used types of exceptions in .NET include:

System.Exception: Base class for all exceptions.
System.NullReferenceException: Thrown when attempting to use a null object reference.
System.IndexOutOfRangeException: Thrown when an array index is out of bounds.
System.InvalidOperationException: Thrown when a method call is invalid for the object’s current state.
System.ArgumentException: Thrown when an argument provided to a method is invalid.
System.ArgumentNullException: Thrown when a null argument is passed to a method that does not accept it.
System.ArgumentOutOfRangeException: Thrown when an argument is outside the allowable range of values.
System.IO.IOException: Thrown when an I/O error occurs.
System.NotImplementedException: Thrown when a requested method or operation is not implemented.
System.DivideByZeroException: Thrown when attempting to divide by zero.