Ultimately, the author of an interactive text will have to evaluate the effectiveness of the design decisions that they have made. How easy is the text to use? How effectively does it convey its content? Is the conveyed content the same as the intended content? How memorable is the interaction? How difficult? How enjoyable? And how do the answers to these questions depend on the characteristics of user and environment? These are just some of the questions that authors must answer if they wish to determine the degree to which their text has achieved its goals. Answering reliably usually involves a repeated cycle of design and testing.