Introduction to .NET Framework 3.0/Nullable Types

.NET 3.0 supports nullable data types. Previously, nullification of only 'int' values were supported by .NET. However, this addition comes as a big boon to developers who might find it easy even to have 'null date-time' values and the kind. Values might be nullifed in .NET by placing a '?' after the datatype name in the variable declaration

Examples int? num = null; DateTime? dt = null;

Note: Nullable support is available since .Net 2.0