Usability replaced the outmoded label “user friendly”way before in 1990. With user point of view, it is all about his/her experience on the design element in terms of usage how much work and satisfaction/frustration he/she experiences using it); and the view of the user’s performance, which involves how easy the product is to use, if it’s to be used in the real world.

A usable interface has three main outcomes:

• It should be easy for the user to become familiar with and competent to use.
• It should be easy for users to achieve their objective through using the design. 
• It should be easy to recall the user interface and how to use it on navigation. 

e.g. a good design on the travel agent’s site means the user should learn from the first time and book a second ticket just as easily.

We can measure usability throughout the development process, from wireframes to prototypes to the final deliverable. Testing can be done with paper and pencil but also remotely when we have higher-fidelity prototypes. The key element of User Experience;

• Usability
• Useful content
• Accessibility
• Credibility

It’s all about art, imagination and building element with ease of use and most efficient ways. Since last many years it has change its principle significant to become more and more personalised which has given new dimension to it.