The Extensible Markup Language (XML), a simplified version of the Standard Generalized Markup Language (SGML), was developed for the exchange of structured data on the Internet. This allows information to be structured not only in a uniform, media-independent format, but also the principles of structuring themselves can be described by a formal set of rules, a grammar. Only then are further processing processes such as guided data entry, data conversion, flexible navigation, and viewing of the data possible. In addition to basic information modeling, a new aspect has emerged with meta-structuring through so-called architectures: the object-oriented layering of structure grammars. This book presents both elementary and architectural structuring techniques for the first time in a coherent form.