This paper identifies World Wide Web site characteristics and attributes and groups them in a hierarchy. The primary goal is to classify the elements that might be part of a quantitative evaluation and comparison process. In order to effectively select quality characteristics, different users' needs and behaviors are considered. Following an introduction, an overview of the Web-site QEM (Quality Evaluation Method) is presented. The following steps that evaluators should follow in applying the Web-site QEM are described: (1) selection of the site domain to evaluate or compare; (2) specification of goals and user standpoint; (3) definition of quality characteristics and attributes; (4) definition of attribute evaluation criteria and determination of elementary preferences; (5) aggregation of elementary preferences to yield the global quality preference; and (6) analysis and comparison of partial and global quality outcomes. More than 60 directly measurable Web site characteristics and attributes are then outlined regarding the visitor standpoint and sites ranging from museums and academic sites to electronic commerce domains. These are organized into the broad categories of usability, functionality, site reliability, and efficiency. (Contains 15 references.) (MES)