Parsing is the process of assigning structure to sentences. The structure is obtained from the grammatical description of the language. Both in Computer Science and in Computational Linguistics, context-free grammars and associated parsing algorithms are among the most useful tools. Numerous parsing algorithms have been developed. Special subclasses of the context-free grammars have been introduced in order to allow and induce efficient parsing algorithms. Special superclasses of the context-free grammars have been introduced in order to allow use of variants of efficient parsing methods that had been developed for context-free grammars. At first sight many parsing algorithms seem to be different, but nevertheless related. Some unifying app...