11 Usability 易用性

Any darn fool can make something complex; it takes a genius to make something simple.
任何该死的傻瓜都能把事情搞复杂；做一件简单的事需要天才。
—Albert Einstein

Usability is concerned with how easy it is for the user to accomplish a desired task and the kind of user support the system provides. Over the years, a focus on usability has shown itself to be one of the cheapest and easiest ways to improve a system’s quality (or more precisely, the user’s perception of quality).

易用性是指用户完成所需任务的容易程度，以及系统提供的用户支持类型。多年来，对易用性的关注已经证明是提高系统质量（或者更准确地说，用户对质量的感知）的最廉价、最简单的方法之一。

Usability comprises the following areas:

易用性包括以下几个方面：

• Learning system features. If the user is unfamiliar with a particular system or a particular aspect of it, what can the system do to make the task of learning easier? This might include providing help features.
  学习系统功能。如果用户不熟悉某个特定系统或其特定方面，系统可以做些什么来简化学习任务？这可能包括提供帮助功能。
• Using a system efficiently. What can the system do to make the user more efficient in its operation? This might include the ability for the user to redirect the system after issuing a command. For example, the user may wish to suspend one task, perform several operations, and then resume that task.
  使用系统的效率。系统能做些什么来提高用户的操作效率？这可能包括用户在发出命令后重定向系统的能力。例如，用户可能希望暂停一项任务，执行多个操作，然后恢复该任务。
• Minimizing the impact of errors. What can the system do so that a user error has minimal impact? For example, the user may wish to cancel a command issued incorrectly.
  尽量减少错误的影响。系统可以做些什么，以使用户错误的影响最小？例如，用户可能希望取消错误发出的命令。
• Adapting the system to user needs. How can the user (or the system itself) adapt to make the user’s task easier? For example, the system may automatically fill in URLs based on a user’s past entries.
  使系统适应用户需求。用户（或系统本身）如何调整以使用户的任务更容易？例如，系统可能会根据用户过去的条目自动填写URL。
• Increasing confidence and satisfaction. What does the system do to give the user confidence that the correct action is being taken? For example, providing feedback that indicates that the system is performing a long-running task and the extent to which the task is completed will increase the user’s confidence in the system.
  增加自信和满足感。系统如何让用户确信正在采取正确的行动？例如，提供反馈，表明系统正在执行长期运行的任务，以及任务完成的程度将增加用户对系统的信心。