UI (User Interface) Design represents the graphical side of the project. This design is based on the sketches that are made at the begin stage of website/application development and on the technical requirements. The UI development stage includes deciding on whether to include animation or video-backgrounds, and on choosing a unique layout in order to stand out. Thus, UI covers all graphical elements that move the development project to the next level.
UX (User Experience) Design is the more analytical and technical part of website/application development. It involves the process of improving the convenience, and hence the pleasure, of navigating through the website/app. A well designed UX, will make the interaction of your customers with your product a satisfying experience, which, in turn, will foster customer loyalty.
Interaction design helps assuring high-level usability of your website/application. This design covers all dynamic elements, such as links, buttons, and forms, and takes care of all the actions that have to follow them.
The main output of interaction design is the sitemap.
Why is this step needed?
This step assures a user-friendly process of registering, ordering, contacting, and finding new information about your company. An unclear or ill-functioning website or applicaton will annoy your users and this negative experience will then be associated to your brand. In effect, this will lower the chance for these users to become potential customers or clients. Giving this step the time that it needs to make using your website/applicaiton a pleasurable experience will thus lead to the opposite, and hence foster an increase of sales.