Since, in lower Mesopotamia, the first steps to document indexing simple principle-in tags where the content of document-was noted, until the arrival of modern automated processes occurred indexing has been a core activity for libraries dedocumentación and other centers, although it was not until the 1970s when they began making efforts to establish its theoretical foundations, to complement theory with practical or reliable to propose rules in practice. Exposure of abundant knowledge we have today about the processes of indexing, and the close relationship with the practice are the pillars of this Manual indexing, which fills a major gap in the Spanish literature. Throughout its six chapters, in this work the interface between cognition and indexing, qualities, standards, regarding the recovery or the presence of indexation on the Internet or the usual tools that work explained indexers; indexing process both in natural language and controlled language crumbles, explains how different types of document indexing and indexing policies of large document databases are analyzed; the contributions that different disciplines are trying to solve such a complex automation task indexing process are studied; is carefully describes the main tools used in the automatic indexing systems, and presents, finally, a prototype designed by the author himself, called Sisa (Semiautomatic Annotation System). The ordering of the chapters, the way the issue is addressed, including the many examples, explanatory notes at the end of each chapter and provided literature (primary and one for the reader to delve into the matter