With the rapid development of information technology, the World Wide Web has been widely used in various applications, such as search engines, online learning and electronic commerce. These applications are used by a diverse population of users with heterogeneous backgrounds, in terms of their knowledge, skills, and needs. Therefore, human factors are key issues for the development of Web-based applications, leading research into human factors to grow significantly in the past decade. This paper identifies and reviews three important human factors that have been examined in existing empirical studies, including gender differences, prior knowledge, and cognitive styles. The main results from the analysis include that: (a) females have more disorientation problems than males; (b) flexible paths are more beneficial to experts while structured content is more useful to novices; and (c) Field Dependent and Field Independent users prefer to employ different search strategies. In addition to reviewing the existing empirical studies, this paper also highlights areas of future research.