Subject headings are usually derived from a controlled vocabulary of terms to which indexers must adhere to ensure consistency of content description. Synonyms Words with the same or similar meaning. A thesaurus provides lists of synonyms. It may also contain lists of alternative or related terms, as well as broader and narrower terms. Thesauri are available in print and electronic formats.
Many electronic databases incorporate a thesaurus.
Topic mapping Topic mapping is a technique which is an extension of brainstorming. A topic map is a graphical representation of the relationships between the keywords and concepts which have been identified through brainstorming. Web A part of the Internet which uses hypertext connections to link documents both internally and externally.