Just about everyone has used the internet these days, and many of us rely on it to connect with families, run our businesses, live our life and manage nearly all aspects of daily activities. What makes online systems easier to use, is clear navigation and experience by means of both a UI and UX Design.
User Interface (UI) is the face-value tools, in which a user can interact with a website, web app, database or front-facing system. This is not entirely exclusive to websites; as nearly every digital device has some form of GUI (Graphical user interface), including desktop operating systems, mobile devices, smart TVs, car dashboards or whitegoods appliances. It is the means in which information is communicated either to, or from, a computer device.
Ideally, a UI is best suited to its use case. As there are so many different uses for a computer system, it is nearly impossible to design a single user interface which suits every possible use case; An example may be using a Linux terminal to run a remote server, is very different to running a Macbook Air; Both server a purpose, one user interface is entirely focused on resource conservation and functionality, another is very resource-hungry albeit elegant, attractive and easy to navigate.