User Interface Design Principles 

User Interface is a very important factor when we design our application (project). User interface provides a mechanism for end users to interact with the application. End users are called target audience. Designing a good user interface which is easy to use and understand is crucial for a successful application. If you already know the target audience for whom you are developing the application then designing becomes simple as you will already be familiar with their corporate colors and likes. Target audience, for example, can be the employee's of a firm for whom you will design the application. A well designed user interface makes it easy and simple for the target audience to understand and use. On the other hand, a poorly designed user interface will be hard to understand and use and can lead to distraction and frustration.

Good user interface is possible if it is designed keeping in mind the following four principles:

1) Simplicity
2) Positioning of Controls
3) Consistency
4) Aesthetics

The image below is an example of a good user interface design.

The above said four principles explained:

Simplicity

Simplicity is a key factor when designing a user interface. If a user interface looks crowded with controls then learning and using that application will be hard. Simplicity means, the user interface should allow the user to complete all the required tasks by the program quickly and easily. Also, program flow and execution should be kept on mind while designing. Try to avoid use of flashy and unnecessary images that distract the user. The simpler the user interface, the more friendly and easy it will be.

Positioning of Controls

Positioning of controls should reflect their importance. Say, for example, if you are designing an application that has a data-entry form with textboxes, buttons, radio buttons, etc. The controls should be positioned in such a way that they are easy to located and matches the program flow. Like, a submit button should be placed at the bottom of the form so that when the user enters all the data he can click it straight away. The image above is a perfect example of positioning of controls.

Consistency

The user interface should have a consistent look through out the application. The key to consistency lies during the design process. Before developing an application, we need to plan and decide a consistent visual scheme for the application that will be followed throughout. Using of particular fonts for special purposes, using of colors for headings, use of images, etc are all part of consistency.

Aesthetics

An application should project an inviting and pleasant user interface. The following should be considered for that.

Color

Use of color is one way to make the user interface attractive to the user. The color which you select for text and back-ground should be appealing. Care should be taken to avoid gaudy colors that are disturbing to the eye, for example, black text on a red back-ground.

Fonts

The fonts which you use for text should also be selected with care. Simple, easy-to-read fonts like Verdana, Times New Roman should be used. Try to avoid bold, strikeout text in most parts of the application. Use of bold, italics and other formatting should be limited to important text or headings.

Images

Images add visual interest to the application. Simple, plain images should be used wherever appropriate. Avoid using flashing images and images that are not necessary but are used only for show off.

Shapes and Transparency

.NET Framework provides tools that allow us to create forms and controls with different levels of opacity. Apart from using traditional shapes like rectangles, etc, these tools also allow us to draw our own shapes which can provide some very powerful visual effects. User drawn shapes should be used only if the application requires it and care should be taken that the shapes which are drawn do not disturb the eye.

The image below is an example of a poorly designed user interface.