Thesauri play an important role in the organization of information. They are used for both indexing and searching purposes. The primary role of the thesaurus is for information retrieval (Aitchison et al., 2000). This is the most important function of a thesaurus and it accomplishes this task by creating a wide scope of information for the indexer and or searcher. The secondary roles of a thesaurus are to help searchers or indexers with a general comprehension of the subject area, outline inter-relationships between concepts, and provide definitions of terms (Aitchison et al., 2000).

Thesauri use a controlled vocabulary to create a set of indexing terms. This may be seen as a bit of a drawback due to the influx of natural language search engines which are now popular. However, both controlled vocabulary and natural language have their advantages and disadvantages. The biggest advantage to using a controlled vocabulary is that index terms can be assigned more weight than natural language terms when searching and, therefore, can create more comprehensive search results (Aitchison et al., 2000).

When creating a thesaurus there are a few things to keep in mind. The most important aspect to consider is the user group and the subject field. By looking at these two items the level of specificity the thesaurus most adhere to can be surmised. For this thesaurus, the user group is made up of librarians, students in library science, and other information professionals. The quantity and type of literature along with language considerations must also be taken into account. Finally, financial and staff resources must also be considered when creating a thesaurus (Aitchison et al., 2000).

There are four basic steps to create a thesaurus. The first step is to pull together a list of original terms from a list of subject statements. The next step is to create a facet analysis of these terms. The terms must then be placed in relationships and the last step is to produce a final term selection. The details of each step are outlined in the following sections.