Welcome to the world of knowledge organisation! Let's start by understanding the meaning of knowledge organisation and knowledge organisation systems.

Knowledge organisation (KO) is an important discipline within information science. It is primarily concerned with the practices of institutions such as libraries, archives, and museums in organising, cataloguing and classifying resources for communities of users (e.g., researchers, students, the public or staff). However, the need to systematically organise information has become universal in the digital age. Therefore, ad hoc solutions by those unfamiliar with KO to manage new data collections may suffer from sustainability, scalability or tractability issues and challenges commonly faced by DH researchers (Golub, Kamal & Vekselius 2021).

KO is about activities such as document description, indexing, and classification performed in libraries, bibliographical databases, archives, and other kinds of "memory institutions" by librarians, archivists, information specialists, subject specialists, as well as by computer algorithms and laymen; for these purposes, rules and standards are developed, including classification systems, lists of subject headings, and thesauri (Hjørland, 2008, 2016).

Natural languages are made up of a large number of terms that are characterised by synonymy (different terms representing the same concepts), homonymy (same terms representing different concepts),  and polysemy (one term having different meanings). These characteristics cause problems when searching for information. To address them, we need controlled languages that disambiguate homonyms, bring together synonyms, and establish other relevant relationships such as hierarchical (e.g., painting is a broader term than oil painting, pastel painting, spray painting, etc.). Hierarchical and more types of relationships allow the user to find fewer but more relevant documents; for example, when entering 'painting' as a search term, the system can then access the Knowledge Organisation System (KOS) and ask the user 'Are you looking for any of the more specific types of painting, such as oil painting…'. And the other way around, if the user uses a too specific term with too few documents, e.g., 'drip painting', the system can resort to the KOS to ask the user, 'Would you also like to see related types of painting such as oil painting…' to increase the number of retrieved documents that could also be relevant. In this way, the user also learns about the context they are exploring from the KOS. 

And what is a KOS? The term knowledge organisation system is intended to encompass all types of schemes for organising information and supporting knowledge management, with a single objective: to arrange content to support retrieval of relevant items (Hodge 2000). 

Knowledge organization system is a generic term used for referring to a wide range of items (e.g. subject headings, thesauri, classification schemes and ontologies), which have been conceived with respect to different purposes, in distinct historical moments. They are characterized by different specific structures and functions, varied ways of relating to technology, and used in a plurality of contexts by diverse communities. However, what they all have in common is that they have been designed to support the organization of knowledge and information in order to make their management and retrieval easier (Mazzocchi, 2018).

Knowledge organisation has existed in one form or another since the beginning of recorded history, but it is more recent as a field of study. KOS, especially those related to the subject representation of information resources, originated in the 19th century, mainly based on philosophical thinking. Although initially conceived for analogue resources, they can now be applied in the digital context. The use of controlled vocabularies remains essential and decisive for the outcome of an information search, for example, to deal with the many synonyms and homonyms that exist in different languages.

Follow the timeline below to discover some historical milestones of the KOS.

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REFERENCES

1. Hjørland, B. (2008). What is Knowledge Organization (KO)? Knowledge Organization, 35(2/3), 86-101. https://doi.org/10.5771/0943-7444-2008-2-3-86
2. Hjørland, B. (2016). Knowledge organization. Knowledge Organization, 43(6), 475-84. https://doi.org/10.5771/0943-7444-2016-6-475
3. Hodge, G. (2000). Systems of Knowledge Organization for Digital Libraries: Beyond Traditional Authority Files. Washington, DC: Council on Library and Information Resources. Available at http://www.clir.org/pubs/reports/pub91/contents.html
4. Mazzocchi, F. (2018). Knowledge organization system (KOS). Knowledge Organization, 45(1), 54-78. https://doi.org/10.5771/0943-7444-2018-1-54