The level of control provided by a system should be related to the proficiency and experience levels of the people using the system. Since accommodating multiple methods increases the complexity of the system, the number of methods for any given task should be limited to two—one for beginners, and one for experts. Beginners do best with a reduced amount of control, while experts do best with greater control.

Beginners benefit from structured interactions with minimal choices, typically supported by prompts, constraints, and ready access to help.

Experts benefit from less structured interactions that provide more direct access to functions, bypassing the support devices of beginners.

Since accommodating multiple methods increases the complexity of the system, the number of methods for any given task should be limited to two—one for beginners, and one for experts.

When possible, we should use a method that is equally simple and efficient for beginners and experts. Otherwise, provide methods specialized for beginners and experts.