Similar to an onion, user experience has many layers. It is something we frequently deal with at Search Discovery. Since the web is so dynamic, it is important to understand users’ expectations for a website. One interesting layer to the onion is that websites have both a software/tool experience as well as a uniquely web experience. This is explained well in this infographic outlining the duality.
Peter Moreville, a thought leader in UI and UX outlines the experience onion in the graphic below. According to his process a site must be usable, useful, desirable, accessible, credible, findable, and valuable. I’d add that not all these layers are guided by web design alone – an understanding of architecture, SEO, and psychology is also required. There is a great amount of thinking that goes into the structure and presence of a successful site. If you are starting from scratch, here is a pdf that explains the design process in a fun way.