2. Description of Web resources

Without going into a detailed description of the Web, it may be useful, for the understanding of what follows, to recall how the Web works. The Web can be seen as a network enabling the exchange of information based on :

• a resource identification mechanism (URIs): a "resource" refers to all or part of a Web page, whether text, image or sound;

• resource representation formats (XHTML, XML) and encoding formats (Unicode): the universality of the Web, open to all languages and cultures, requires support for different character encodings, leading to the adoption of Unicode;

• a resource exchange mechanism: several communication protocols can be used, depending on whether HTML documents (HTTP: HypertText Transfer Protocol), files (FTP: File Transfer Protocol) or messages (SMTP: Simple...