HTML Syntax Checking
Syntax-checking programs have been developed for programming languages and markup languages. Syntax checkers for HTML and other Web standards analyze the quality of Web pages from the perspective of software engineering.• Syntax (Are all open tags closed? Are language elements used syntactically correct?)
• HTML use (Is the sequence of the headings consistent?)
• Structure of a site (Are there links that lead one hierarchy level up?)
• Portability (Can all expressions be i
• Stylistic problems (Is alternative text provided for graphics? Do words like here appear in link text?)
Link Analysis
One of the main challenges for search engines is the heterogeneous quality of Internet pages concerning both content quality and interface design (Henzinger, Motwani, & Silverstein, 2002). In Web information retrieval, the common approach to automatically measure the quality of a page has been link analysis. However, link analysis is a heuristic method. The number of links pointing to a page is considered as the main quality indicator (Brin & Page, 1998). From the perspective of human-computer interaction, it is assumed that authors of Web pages prefer to link to pages that are easy to use for them. A large variety of algorithms for link analysis has been developed (Henzinger, 2000). The most wellknown ones are probably the PageRank algorithm and its variants (Haveliwala, 2002; Jeh & Widom, 2003). The basic assumption of PageRank and similar approaches is that the number of in- or back-links of a Web page can be used as a measure for the authority and consequently for the quality of a page including its usability.
Quality of Text
If systems for assessing the quality of text succeed, they will play an important role for human-computer interaction. The readability of text is an important issue for the usability of a page. Good readability leads to fast and more satisfying interaction.
PAGE AND NAVIGATION STRUCTURE
Advanced quality models that take several aspects into account are still at an experimental stage. However, they are the most relevant for humancomputer interaction. These systems go beyond syntax checking and analyze the design of pages by extracting features from the HTML code of pages. Prototypes consider the use of interaction elements and design, for example, by looking for a balanced layout.Automatic evaluation allows users and developers to evaluate many interfaces according to their usability. Systems for automatic evaluation will help to identify well-designed interfaces as well as good interface elements. The evaluation of a large number of Internet interfaces will reveal trends in interface design and identify design elements often and successfully used. .