View source for Usability

Wikipedia defines Usability as:

:The ease with which people can employ a particular tool or other human-made object in order to achieve a particular goal. 

The Wikipedia definition appears to be a simplified version of the definition of [[Software Usability]] given by the International Organization for Standardization (IOS).

The term "user friendly" is often used as a synonym for usable. The Wikipedia article however advises that the term "user friendly" should be avoided, as it has no widely accepted definition and is thus often used without much substance. 

The term [[Ergonomics]] (consideration of human factors in design) is related to usability, although the relationship is diversely interpreted. Some think of usability as a specialised branch of [[Ergonomics]] that deals with software design. Others view these topics as complementary, with [[Ergonomics]] focusing on physiological matters (e.g. turning a door handle), and usability focusing on psychological matters (e.g. recognising that this door can be opened by turning that handle).

The concept of Usability is at present particularly used in the design of:
*Human-computer interactions for computer programs or web sites
*Consumer electronics products 
*Knowledge transfer objects or systems such as hard-copy documents or online help software

However, since "usability" may apply to any tool or other human-made object, it can also refer to the efficient design of mechanical objects such as a door handle or a hammer.

The term [[User-Centered Design]] refers to the design of objects or products with the user's psychology and physiology in mind. Going one step further, [[User-Driven Design]] or [[Participatory Design]] refer to a process in which some of the users become actual or de facto members of the design team.

==Criteria of Usability==
An object or product has high "usability" to the extent that it is:
*Effective for its purpose
*Efficient to use
*Easy to learn to use
*Reliable
*Adaptable and extensible
*Accommodating to a variety of users
*Satisfying to use

An object is '''effective''' if it is fit for its purpose, and can be used to complete the desired task. A shovel is effective for digging a trench, but a spoon is not. Another word for effectiveness is utility.

An object is more '''efficient''' than another if it permits achieving the purpose with less work or time. For digging a trench, an excavator is a more efficient tool than a shovel. Usability experts are generally more concerned with efficiency than with effectiveness, since few products are introduced that are actually ineffective for their purpose. 

The use of an object can be made '''easy to learn''' by designing the object such that its operation can be learned by simply observing the object. An example of an object with high learnability might be an intuitive navigation tool. Related to learnability is '''memorability''', or the ease with which users can recall how to operate the object.

An object is '''reliable''' if it repeatedly proves to be effective and efficient. One aspect of reliability is that the object should operate with few and non-catastrophic errors.

An object is '''adaptable and extensible''' if it is endowed with features that allow it to be adapted or extended to suit new and unpredicted tasks or goals.

An object is '''accommodating''' if it has been designed to accommodate different user populations.

The subjective feeling that use of the object is '''satisfying''' to the user is also an important criteria of usability, though it may be more difficult to describe precisely than some of the other criteria .

==Additional Usability Topics==
Usability is a rapidly expanding field. Additional specific topics in usability include the following:
*Web Usability: usability in the context of web browsers: http://en.wikipedia.org/wiki/Web_usability
*Universal Usability: usability for all type of users, in particular those with handicaps (related to Accessibility): http://en.wikipedia.org/wiki/Universal_usability
*Accessibility: http://en.wikipedia.org/wiki/Accessibility"> 
*User-Centered Design: design for usability: http://en.wikipedia.org/wiki/User-centered_design
*Usability Testing: how to measure usability: http://en.wikipedia.org/wiki/Usability_testing

==Links==
*http://en.wikipedia.org/wiki/Usability
*http://en.wikipedia.org/wiki/Ergonomics
*http://en.wikipedia.org/wiki/User-centered_design
*http://en.wikipedia.org/wiki/Participatory_design
*The best-known usability guru is Jakob Nielsen, pioneered the systematic approach to designing usable computer interfaces, notably for websites: http://www.useit.com 
*Neilsen’s best-known article is the following: Top Ten Mistakes in Web Design: http://www.usabilitynet.org/management/b_mistakes.htm
*Another well-constructed usability site was produced as an EU-funded project: http://www.usabilitynet.org/home.htm
*James Horn provides a website devoted to usability testing, James Horn's Usability Methods Toolbox: http://jthom.best.vwh.net/usability

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