“User needs first: Technology second” – Don Norman
Whenever we think of designing a physical product, a computer interface, new software or anything a human can interact with, we should always in mind who the final targets are. Users represent the key element that defines whether any kind of product is easy to use. Here is where usability appears.
Usability is a very controversial subject debated by many researchers in their studies . The most common and simple definition I found about usability is that it represents “the ease of use” something. A formal definition according to ISO-9241 is that usability is about “effectiveness, efficiency and satisfaction with which specified users achieve specified goals in particular environments”. And this is how they define each characteristic:
- effectiveness: the accuracy and completeness with which specified users can achieve specified goals in particular environments
- efficiency: the resources expended in relation to the accuracy and completeness of goals achieved
- satisfaction: the comfort and acceptability of the work system to its users and other people affected by its use
We can expand this definition by using the following properties: “intuitive design, ease of learning, efficiency of use, memorability, error frequency and severity, subjective satisfaction”. A combination of these characteristics are extremely important in order to better describe usability.
In my opinion, usability is a complex concept and it is difficult to limit its definition. But if if we had to make a synthesis of how usability is defined by experts in the area, we could also describe it as the quality and efficiency of a product regarding the satisfaction of users’ goals.
Usability user vs. user experience(UX)
It is sure that usability is fundamental when it comes to exploring technology by respecting users values and objectives. But when it comes to providing users a valuable experience, it is very easy to fall into the trap: does an easy-to-use system necessarily offer good experience? And is a beautiful design necessarily easy or intuitive to use? For both questions the answer is NO. Usability is different from how the user feels during his/her interaction with a system.
- Usability ≠ UX
- Usability is about getting something done intuitively and easily
- UX is about users’ emotional connection to the task
- Usability + UX are essentials for a good product
Related links:  - http://www.w3.org/2002/Talks/0104-usabilityprocess/slide3-0.html  - http://www.usability.gov/what-and-why/usability-evaluation.html