The third aspect of importance in any Information Storage and Retrieval System relates to its retrieval capabilities. Retrieval process is the most important issue and basically depends on how the information contained in the system has been indexed and how it is stored in the system. In other words, the indexing and storage aspects determine, to a large extent, the search strategy to be adopted for retrieval of information. Another factor which influences the retrieval process. is the system user and the queries that are submitted to the system, which do not, in general, change with the system. The user's needs may not change with the availability of a particular system, although they may become more sophisticated as the user's experience with the system increases.
i) Retrieval can be conceptualised as involving three important stages: Accepting as input a query (as a representation of information need) formulated by the user;
ii) carrying out a comparison of the query with each of the records (representations of document in a database; and
iii) producing as output, for consideration by the user, a retrieved set of records identified on the basis of this comparison.
Many searchers will pass through these three stages many times before completing a search. It may be stated that dialogue design styles, indexing and searching languages, search logic, and search facilities all influence the effectiveness of the retrieval.