Amiya Kumar Das

KEYWORDS The terms 'unified index' and 'unified search index' libraries are getting associated with discovery services. Discovery services are that unified search index to search content from all sources they have access to from a single index. It ia single and simply entry point which searches the single entry point which searches the pre-indexing metadata and fulltext documents. Similarly web scale discovery services have become major potential tools to transform the nature of library system. These services are capable of information retrieval quickly and seamlessly across a vast range of local and remote content and providing relevancy-ranked result in the type of individual interface that today's information seekers expect of information retrieval. This paper discusses how a discovery solution works and provides the potential features of discovery solutions. It is also enumerates the benefits of web discovery interface. It describes the major discovery solution providers in libraries. information retrieval, web scale discovery, discovery tools, OCLC, EBSCO.