Learn Python

Use the del statement: del variable_name. After deletion, attempting to access the variable raises a NameError. This is useful for freeing memory or removing a name from scope intentionally. 

== checks if two variables have the same value, while is checks if they point to the same object in memory. For example, [1,2] == [1,2] is True, but [1,2] is [1,2] is False because they are two different list objects. Use is only when checking identity (e.g. x is None). 

Yes. Python allows reassigning a variable to a completely different type — x = 5 followed by x = "hello" is valid. This is called dynamic typing. While flexible, it can reduce readability, so use type hints and keep variable roles consistent. 

A local variable exists only inside the function where it is created and cannot be accessed outside. A global variable is defined at the module level and can be read anywhere in the file. To modify a global variable inside a function, use the global keyword. 

No. Python is dynamically typed, so you simply assign a value and Python infers the type automatically. You can optionally add type hints (x: int = 5) for readability and tooling support, but they are not enforced at runtime.