Null

The null data type has only one value, null. This value means "no value"—that is, a lack of data. The null value can be used in a variety of situations. Here are some examples:

• To indicate that a variable has not yet received a value
• To indicate that a variable no longer contains a value
• As the return value of a function, to indicate that no value was available to be returned by the function
• As a parameter to a function, to indicate that a parameter is being omitted