In Python, you can determine the type of a variable using the type() function, which returns the type object of the variable. For more robust type checking, especially when subclassing is involved, isinstance() is preferred as it checks if an object is an instance of a class or a tuple of classes. This is particularly useful in polymorphic scenarios where an object may belong to a hierarchy of types. Proper type checking is vital in dynamic typing environments to ensure that operations on variables are valid and to avoid runtime errors.