| What
is Usability?
Usability addresses the relationship between tools and their users.
In order for a tool to be effective, it must allow intended users
to accomplish their tasks in the best way possible. The same principle
applies to computers, websites, and other software. In order for
these systems to work, their users must be able to employ them effectively.
What makes a website or piece of software
usable?
Usability depends on a number of factors including how well the
functionality fits user needs, how well the flow through the application
fits user tasks, and how well the response of the application fits
user expectations. We can learn to be better user interface designers
by learning design principles and design guidelines. But even the
most insightful designer can only create a highly-usable system
through a process that involves getting information from people
who actually use the system. Usability is the quality of a system
that makes it easy to learn, easy to use, easy to remember, error
tolerant, and subjectively pleasing.
Why is Usability Important?
From the user's perspective usability is important because it can
make the difference between performing a task accurately and completely
or not, and enjoying the process or being frustrated. From the developer's
perspective usability is important because it can mean the difference
between the success or failure of a system. From a management point
of view, software with poor usability can reduce the productivity
of the workforce to a level of performance worse than without the
system. In all cases, lack of usability can cost time and effort,
and can greatly determine the success or failure of a system. Given
a choice, people will tend to buy systems that are more user-friendly.
How Do You Achieve a High Level of Usability?
The key principle for maximizing usability is to employ iterative
design, which progressively refines the design through evaluation
from the early stages of design. The evaluation steps enable the
designers and developers to incorporate user and client feedback
until the system reaches an acceptable level of usability.
The preferred method for ensuring usability is
to test actual users on a working system. Achieving a high level
of usability requires focusing design efforts on the intended end-user
of the system. There are many ways to determine who the primary
users are, how they work, and what tasks they must accomplish. However,
clients' schedules and budgets can sometimes prevent this ideal
approach. Some alternative methods include user testing on system
prototypes, a usability inspection conducted by experts, and cognitive
modeling.
Where is Usability Applied?
Usability is one of the focuses of the field of Human-Computer Interaction.
As the name suggests, usability has to do with bridging the gap
between people and machines. A user interface (or human-computer
interface) refers to the parts of a hardware and/or software system
that allow a person to communicate with it. This includes output
devices (the way the computer talks to a user) and input devices
(the way a user talks to the computer). Typical "output devices"
include computer monitors and the windowing systems that run on
them, but also include speakers and other devices that provide feedback.
"Input devices" include peripherals like keyboards, mice,
and joysticks, but also include microphones and even eye movement
devices. Each of these interface components has devices corresponding
to the visual (sight), aural (sound), and haptic (touch) channels
of the brain. Usability engineering studies these elements of the
user's experience.
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