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標準中對網站可用性的定義是：特定用戶在特定環境下，能夠快速、有效且滿意地完成特定的目標。用戶使用網站都是有目標的。 如果設計得好，網站不但會達到用戶的目標，還會將其與自身公司的目標聯系起來。介乎用戶目標和公司目標之間的往往就是表單
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: