Identify and describe three levels of consistency.

Consistency with and across platforms. This means the application's controls are consistent between Windows and Apple. Or even within the Windows applications.
 Consistency within a suite of applications. Often a company will have several products that work together or that consist of several related apps within a suite. The controls and layout of the user interface should be consistent.
 Consistency within an application means that the look and feel of an application across its various forms and pages is the same with the same types of controls and placed in the same places on the form or page.