Could you explain what the term 'nullable' means in programming?

In programming, the term "nullable" means that a variable or object can hold the value null, which indicates the absence of a value.

In C#, reference types are nullable by default, and for value types (such as int, bool), a special syntax is used for nullable types:

int? nullableInt = null;

This allows the variable nullableInt to hold either an integer value or null.

Nullable types are useful for indicating the absence of a value, for example, when data may be undefined or missing, which is common when working with databases or user input.