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

ii.Clarity:

• User interface must be clear in visual appearance,concept & wording.
• Visual elements should be understandable & related to real world concepts & functions.Analogies should be simple.
• Interface words & text should be simple,unambiguous,& 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 & they think, feel & behave differently compared to the developer.
• Task & job compatibility:The structure & 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 & reduce the necessity for new learning.

iv.Comprehensibility:

• The steps to complete a task should be obvious.System should be understandable & 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 & how to do it.

v.Configurability:

• A default configuration as well as easy personalization & customization through configuration and reconfiguration should be provided.
• Customization enhances sense of control,encourages an active role in understanding & allows personal preferences & 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 & never be interrupted for errors.
• Actions should result from explicit user requests & be performed quickly.

viii.Directness:

• Tasks should be performed directly & alternatives should be visible reducing the user’s mental workload.
• Tasks are performed by directly selecting an object then selecting an action performed & then seeing the action being performed.

ix.Efficiency:

• Transition between various systems controls should flow easily & freely.
• Navigation paths should be as short as possible.
• Eye movement through a screen should be obvious & sequential.

x.Familiarity:

• Build into the interface concepts,terminology,workflows & spatial arrangements already familiar to the user.
• Familiar concepts enable people to get started & become productive quickly.

xi.Flexibility:

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

xii.Forgiveness:

• People will make mistakes;a system should be able to tolerate those that are common & 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 & 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,& provide uniformity & consistency.

xvii.Transparency:

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