Summary

In code, null_value marks the absence_of_value or a null_reference. It is not_zero_or_empty and is treated as a distinct sentinel. In languages: JavaScript has javascript_null and javascript_undefined; Python uses python_none; Java uses java_null; C# uses csharp_null; C++ uses cpp_nullptr; SQL uses sql_null with three_valued_logic. In many runtimes it is falsy. Common errors include null_pointer_exception and type_error. Related tools: strict_equality, null_checks, null_coalescing (??), and optional_chaining (?.).