The term usability has several definitions in each research field.
In the field of Human–Computer Interaction (HCI) field, the most widely accepted definition of
usability is that proposed in the ISO 9241-11 [18]: ‘‘the extent to which a product can be used by
specified users to achieve specific goals with effectiveness, efficiency and satisfaction in a
specified context of use’’. This definition is that which is closest to the human interaction
perspective. In this view, usability implies the interaction of users with the software product
and can be seen as the product’s capability to meet customer expectations. On the other hand, in
the field of Software Engineering (SE), the most widely accepted definition of usability is that
proposed in the ISO 9126-1 [20]: ‘‘the capability of the software product to be understood,
learned, operated, attractive to the user, and compliant to standards/guidelines, when used under
specific conditions’’. In this view, usability is seen as one specific characteristic that affects
the quality of a software product. It can be evaluated during the early stages of Web development
and does not necessarily imply the user’s interaction with the system since it can be measured as
‘‘conformance to specification’’, where usability is defined as a matter of products whose measurable
characteristics satisfy a fixed specification which has been defined beforehand. These different