The ISO 9241 standard defines website usability as the “effectiveness, efficiency and satisfaction with which specified users achieve specified goals in particular environments.” When using a website, users have a particular goal. If designed well, the website will meet that goal and align it with the goals of the organization behind the website. Standing between the user’s goal and the organization’s goals is very often a form, because, despite the advances in human-computer interaction, forms remain the predominant form of interaction for users on the Web. In fact, forms are often considered to be the last and most important stage of the journey to the completion of goals.
ISO 9241标准中对网站可用性的定义是：特定用户在特定环境下，能够快速、有效且满意地完成特定的目标。用户使用网站都是有目标的。 如果设计得好，网站不但会达到用户的目标，还会将其与自身公司的目标联系起来。介乎用户目标和公司目标之间的往往就是表单
Let’s clarify this last point by discussing the three main uses of forms. As Luke Wroblewski states in his book Web Form Design: Filling in the Blanks, every form exists for one of three main reasons: commerce, community or productivity. The following table translates each of these reasons into the user and business objectives that lie behind them: