Have you visited a website that has utterly confusing with too many links that did not make sense to you and extremely poor interface? On the contrary, did you have a delightful experience of browsing a website that was simple, beautifully designed and had logical flow of pages with smooth navigation?
These two are exactly opposite UI and UX design experiences that would have left contradicting impressions on your minds. Psychological effect of the design of website is a major contributing factor for converting a visitor to customer. Companies have realized the significance of UI and UX design in website development and are investing heavily on this segment.