CSharp: Nullable Types.

In C#, a nullable type is a type that can be assigned a value or the value “null”, indicating that it doesn’t have a value. By default, value types such as int or double cannot be assigned a value of null, but nullable types allow this by wrapping the value type in a Nullable<T> structure. To declare a nullable type, you can use the “?” symbol after the type name. For example, “int?” is a nullable int, and can be assigned either a number or null.