To design is to solve a problem, and Web-site design is no different from any other problem. You must understand the problem, define the goals, plan the steps, and generate a solution. Clearly defining the problem is intricately tied to understanding. Planning involves developing a clear approach and process for solving the problem. Only then can you look at execution. A designer's challenge is to assemble the necessary tools, information, and approach so that Web-site visitors leave more informed than when they arrived. You can track the site's success by motivating visitors to take actions you can measure.
Mok, Clement and Vic Zauderer. New Architect (1997). Design>Web Design