Key Library Science Terms: Definitions Every Reader Should Know

Library science can look deceptively familiar because almost everyone has used a library. Yet the field has its own technical vocabulary, and those terms matter because they describe how libraries organize knowledge, preserve access, teach users, and manage both physical and digital collections. The following terms form a practical working glossary for readers who want to understand what library professionals are actually doing when they build catalogs, evaluate sources, design services, and preserve records for future use. Readers who want to see these terms used in fuller analysis can continue with How Library Science Is Studied: Methods, Tools, and Evidence.

Catalog

A catalog is the structured record of a library’s holdings. It is more than a list of books. A good catalog captures titles, authors, editions, subjects, formats, dates, identifiers, and location information so users can discover and retrieve materials efficiently.

Metadata

Metadata is data about data. In library work, it describes a resource’s title, creator, date, subject, format, rights status, language, and many other characteristics. Strong metadata improves findability, interoperability, and long-term management.

Authority control

Authority control standardizes names, subjects, and titles so related materials file together even when the underlying language varies. It prevents one author from scattering across a catalog under multiple spellings or name forms.

Controlled vocabulary

A controlled vocabulary is a managed set of approved terms used for description and retrieval. Instead of letting every cataloger invent labels ad hoc, a library uses established subject language so records remain consistent and searchable across large collections.

Classification

Classification is the arrangement of knowledge into categories. In libraries, it usually refers to systems such as Dewey Decimal or Library of Congress Classification that group materials by subject so related works are shelved and browsed together.

Call number

A call number is the location-and-subject code assigned to an item. It tells staff where a resource belongs and helps users move from a catalog record to a physical shelf or storage request.

Subject heading

A subject heading is an approved term used to describe what a work is about. Subject headings help readers discover materials even when the language in the title does not match the language of the search.

Discovery layer

A discovery layer is the search interface that sits on top of multiple library systems and databases. It aims to make searching books, articles, media, and digital objects feel more unified than older catalog-only environments.

OPAC

OPAC means online public access catalog. The term is older than discovery layer and often refers specifically to the searchable public interface for catalog records, though many libraries now combine catalog and broader discovery tools.

Collection development

Collection development is the deliberate building, shaping, and reviewing of a library’s holdings. It includes selecting, acquiring, licensing, weeding, and balancing materials to serve the needs of a defined community.

Acquisitions

Acquisitions covers the processes by which the library purchases, licenses, or otherwise obtains resources. It involves budgets, vendors, invoicing, format decisions, and increasingly complex terms for digital content.

Circulation

Circulation refers to the lending and return of library materials, along with policies on checkout periods, renewals, holds, recalls, fines, and item status. It is the service layer most visible to many patrons.

Reference interview

The reference interview is the conversational method librarians use to clarify what a user really needs. A reader may ask for “books on climate,” but the real need might be local flood-risk data, a beginner overview, or peer-reviewed articles for a policy paper.

Information literacy

Information literacy is the ability to locate, evaluate, use, and ethically share information. In modern library science it includes source evaluation, search strategy, authorship questions, evidence standards, and awareness of misinformation.

User experience

User experience, often shortened to UX, refers to how people actually navigate library spaces, websites, catalogs, signage, and services. A strong library system is not merely well organized from the staff perspective; it is usable by real people with varied skills and constraints.

Interlibrary loan

Interlibrary loan, or ILL, is the system through which libraries borrow materials from one another for patrons. It expands access by treating separate collections as part of a wider cooperative network.

Serials

Serials are continuing publications released in successive parts, such as journals, magazines, annuals, and continuing reports. Managing serials requires special attention to holdings statements, licensing, continuity, and access changes over time.

Institutional repository

An institutional repository is a platform that stores and provides access to scholarship and research outputs associated with an institution. It may include articles, theses, datasets, conference papers, and other digital works.

Open access

Open access refers to scholarly content made available online without paywall barriers to readers. In library science, open access is tied to research dissemination, licensing models, equity of access, and long-term preservation.

Digitization

Digitization is the process of converting analog materials into digital form. It is not identical to preservation, though it often supports preservation and access. Good digitization requires attention to image quality, metadata, rights, and file management.

Digital preservation

Digital preservation is the managed process of keeping digital content authentic, usable, and accessible over time. It includes file-format decisions, fixity checking, storage redundancy, metadata, migration planning, and documentation.

Provenance

Provenance refers to the origin and custody history of an item or collection. In libraries and archives, provenance supports authenticity, contextual understanding, and trust in the integrity of materials.

Linked data

Linked data is a way of structuring metadata so entities, relationships, and concepts can connect across systems on the web. For libraries, it offers the possibility of moving beyond isolated catalog records toward richer networked discovery.

Rights metadata

Rights metadata records what is known about copyright, licenses, access restrictions, and permissible uses. It matters because a resource that is perfectly described but legally unusable still fails many user needs.

Preservation copy

A preservation copy is a version of a digital or analog item maintained with long-term stability in mind, usually at higher quality or in a preferred format. It is different from an access copy designed for convenience and delivery.

Why these terms matter together

These terms are connected. Metadata, authority control, and subject headings shape discovery. Collection development, acquisitions, and rights metadata determine what a library can actually provide. Information literacy and the reference interview connect systems to human judgment. Digitization, provenance, and digital preservation ensure that access today does not destroy access tomorrow.

Library science is therefore not just about shelves, screens, or databases in isolation. It is about building trustworthy systems for organizing knowledge, helping users interpret it, and preserving it across changing technologies. Once these terms are understood, the field becomes much easier to read with precision.

MARC

MARC, short for Machine-Readable Cataloging, is a record format developed so bibliographic data can be stored, exchanged, and processed by computers. It played a foundational role in shared cataloging and still shapes large portions of library metadata infrastructure.

Dublin Core

Dublin Core is a simpler metadata schema widely used in digital collections and repositories. Its elements, such as title, creator, subject, date, and format, support interoperability across systems that do not need the complexity of traditional catalog records.

Finding aid

A finding aid is a structured guide to an archival or manuscript collection. It usually includes contextual history, scope notes, series descriptions, and container lists that help users understand what is in the collection and how it is organized.

Repository

A repository is the platform or institution that stores, manages, and provides access to digital or physical collections. In digital preservation, the term often emphasizes system architecture and long-term stewardship rather than simply storage.

Weeding

Weeding is the selective removal or relocation of items from an active collection. It is not the same as careless disposal. In responsible collection management, weeding supports relevance, space planning, safety, condition review, and better use of the collection as a whole.

Interoperability

Interoperability refers to the ability of systems, schemas, or tools to exchange and use data effectively. In libraries, it matters because catalogs, repositories, digital exhibits, and preservation systems often have to work together across institutions.

Fixity

Fixity is the property that allows a digital object to be checked for unintended change. Libraries use checksums and related methods to confirm that stored files remain bit-for-bit stable over time.

Accessibility

Accessibility in library science means designing collections, platforms, interfaces, and services so people with disabilities can discover and use them effectively. It involves captioning, screen-reader compatibility, keyboard navigation, document structure, readable formats, and broader design choices.

Reference collection

A reference collection contains materials intended primarily for in-library consultation, such as encyclopedias, handbooks, legal sets, maps, and specialized tools. Even in digital environments, the concept survives in resources optimized for quick factual or orienting use.

Scholarly communication

Scholarly communication refers to the systems through which research is created, reviewed, shared, preserved, and measured. Libraries engage this area through repositories, open-access support, copyright guidance, publishing partnerships, and metrics literacy.

Why the glossary extends beyond books

Taken together, these terms show why library science is much broader than the casual image of shelving books. The field includes data structures, teaching, preservation, interface design, licensing, repositories, and research communication. A reader who knows this vocabulary can follow professional discussions about discovery, stewardship, and access with far more precision.

Knowledge organization

Knowledge organization is the broader field concerned with how concepts, subjects, and relationships are arranged so people can retrieve and use information. Library science depends on it because every classification scheme, thesaurus, and metadata model makes claims about how knowledge should be structured.

Abstracting and indexing

Abstracting and indexing refer to the creation of summaries and structured subject access for periodical literature and other resources. These services help users identify relevant materials quickly, especially in research environments where article-level discovery matters.

Special collections

Special collections are distinct holdings, often rare, unique, fragile, or locally significant, that require more controlled access and specialized stewardship than general circulating materials. They may include manuscripts, rare books, photographs, maps, ephemera, and institutional archives.

Data curation

Data curation is the ongoing management of research data so it remains documented, usable, shareable, and preservable. It includes file organization, metadata, storage planning, rights review, and preparation for repository deposit or long-term stewardship.

Embedded librarian

An embedded librarian works closely within a course, department, lab, or user community rather than waiting for questions at a generalized service point. The role reflects a shift toward contextualized research support and partnership.

Knowledge graph

A knowledge graph represents entities and their relationships in a networked structure that can support richer discovery and context. In library environments, this idea connects closely to linked data and more flexible ways of expressing bibliographic relationships.

Why terminology is professional infrastructure

Vocabulary in library science is not decorative jargon. It is professional infrastructure. These terms allow librarians, archivists, technologists, instructors, and administrators to coordinate work across acquisitions, teaching, metadata, preservation, assessment, and access. Once the vocabulary becomes clear, the field’s complexity becomes far more understandable.

Once these additional terms are understood, readers can see that library science is a coordinated language for describing discovery, stewardship, teaching, preservation, and public access rather than a loose bundle of familiar library tasks.