The general principles of the user interface can be given as follows:

i. Aesthetically Pleasing:

• A design is aesthetically pleasing if it is attractive to the eye. It draws attention subliminally, conveying a message clearly and quickly.

• Visual appeal is provided by following the presentation and graphic design principles which include meaningful contrast between screen elements, creating spatial groupings, aligning screen elements, providing three-dimensional representation, and using color and graphics effectively.

ii. Clarity:

• User interface must be clear in visual appearance, concept and wording.

• Visual elements should be understandable and related to real world concepts and functions. Analogies should be simple.

• Interface words and text should be simple, unambiguous, and free of computer jargon.

iii. Compatibility:

Compatibility needs to be provided as

• User Compatibility: “Know the user” is the fundamental principle in interface design as no users are alike and they think, feel and behave differently compared to the developer.

• Task and job compatibility: The structure and flow of functions should permit easy transition between tasks. The user must never be forced to navigate between applications or many screens to complete routine daily tasks.

• Product compatibility: compatibility across products must always be considered in relation to improving interfaces, making new systems compatible with existing systems will take advantage of what users already know and reduce the necessity for new learning.

iv. Comprehensibility:

• The steps to complete a task should be obvious. System should be understandable and flowing in meaningful order.

• A user should know what to look at, what to do, when to do it, where to do it, why to do it and how to do it.

v. Configurability:

• A default configuration as well as easy personalization and customization through configuration and reconfiguration should be provided.

• Customization enhances sense of control, encourages an active role in understanding and allows personal preferences and differences in experience levels leading to high user satisfaction.

vi. Consistency:

• Consistency is important because it can reduce requirements for human learning by allowing skills learned in one situation to be transferred to another like it.

• Any new system must impose some learning requirements on its uses but avoid unnecessary activity.

vii. Control: - The user must control the interaction and never be interrupted for errors.

• Actions should result from explicit user requests and be performed quickly.

viii. Directness:

• Tasks should be performed directly and alternatives should be visible reducing the user’s mental workload.

• Tasks are performed by directly selecting an object then selecting an action performed and then seeing the action being performed.

ix. Efficiency:

• Transition between various systems controls should flow easily and freely.

• Navigation paths should be as short as possible.

• Eye movement through a screen should be obvious and sequential.

x. Familiarity:

• Build into the interface concepts, terminology, workflows and spatial arrangements already familiar to the user.

• Familiar concepts enable people to get started and become productive quickly.

xi. Flexibility:

• Flexibility is the system’s ability to respond to individual differences in people.

• Flexibility is accomplished by providing multiple ways to access application functions and perform tasks and also by permitting system customization.

xii. Forgiveness:.

• People will make mistakes; a system should be able to tolerate those that are common and unavoidable.

• A forgiving system keeps people out of trouble.

xiii. Predictability:

• All actions should lead to results the user expects. Current operations should provide clues as to what will come next.

• Design consistency enhances predictability.

xiv. Recovery:

• A person should be able to retract any action by issuing an undo command.

• The goal is stability or returning easily to the right track when a wrong track has been taken.

• Recovery should be obvious, automatic, easy and natural to perform.

xv. Responsiveness:

• A user must be responded quickly.

• Substantial or more informative feedback is most important for the casual or new system user.

• All requests must be acknowledged in some way.

xvi. Simplicity:

• Simplicity can be achieved by progressive disclosure, provide defaults, minimize screen alignment points, make common actions points, make common actions simpler, and provide uniformity and consistency.

xvii. Transparency:

• Permit the user to focus on the task or job without concerning the mechanics of the interface.

• Working and reminders of workings inside the computer should be invisible to the user.

xviii. Trade-Offs:

• Final design will be based on a series of trade-offs balancing often-conflicting design principles.

• People’s requirements always take precedence over technical requirements.