Discovery layer is a term for software used to search libraries. A library's discovery layer includes a search box that library users can type queries into, similar to a web search engine. In library science, this searching is called discovery. The results from discovery may include books and other print materials from the library's catalog, electronic resources such as e-journals or videos, and items stored in other libraries. The word "layer" indicates that the software is modular—it is front-end software, separable from an integrated library system.
Terminology
The term discovery layer has been described as an overarching term that can include:
Discovery system, an interconnected search system, allowing library users to search not only the catalog of library print materials, but various digital resources and perhaps resources located in other libraries. The discovery system queries more than one data source upon a single user request; this is sometimes called federated search.
The term discovery layer can be used to stress "the ‘decoupling’ of catalog search and browse functionality from the integrated library management system." The distinction between discovery layer, interface, and system is not rigorous and the terms are sometimes used as synonyms. These "inconsistencies were in part due to the field’s newness" when the terms were being created.
Users searching for print materials at a library once used card catalogs, and later computerized catalogs called OPACs. Searching for resources other than material in the catalog, such as electronic resources, was done with separate tools. Using card or computerized catalogs well required skills and jargon particular to libraries. As computerization advanced, OPACs were integrated with other library systems, like acquisition and circulation systems. The resulting monolithicsoftware systems were named integrated library systems.
Changing expectations
As the web became more widespread, library users developed "the expectation of being able to discover the collection in a search engine style." Gradually, discovery interfaces were created to be more forgiving of misspellings and punctuation choices than historical OPACs, and to offer features like suggestion of related search terms and faceted search. Reference librarians in the mid-2000s also spent "a lot of time talking about information silos." They were concerned that library users had to hunt for various types of resources with various tools, an obstacle to users, resulting in underused resources. Librarians sought multidatabase search products that would collapse the silos.
These two features, search-engine-like interfaces and multidatabase search, began to appear in the same software systems. One author dates the uniting of these features to 2009; this would be the invention of the discovery system. Particularly if decoupled from an ILS, this united product can also be called a discovery layer. "The discovery layer still uses the information and indexing in the integrated library system, but it also searches across proprietary databases and other electronic resources, all with the goal of revealing everything that a library owns or has licensed on a given topic be it a print monograph, an electronic journal article, streaming video, or a collection of archival documents" The discovery layer can be looked on as the replacement for the OPAC. Some libraries maintain both a catalog interface OPAC and a discovery layer interface.
Examples
Some discovery layer or discovery service products are modules of a particular ILS or database product, and are sold by that product's vendor. An example is EBSCO Discovery Service. Other discovery tools are free-standing software products. Blacklight and VuFind are open-source examples.
