Controlled Vocabulary

A controlled vocabulary is a list of words to tag units of information in a text or document. Controlled vocabularies can be used for information retrieval.

In the context of information retrieval, or knowledge graphs 1 often the term "vocabulary" is used for brevity.

The Role of Controlled Vocabularies in KGO

Controlled vocabularies, or vocabularies, are used to standardize common information across different sources of documents. This standardization is especially helpful for the World Wide Web, where documents for varying contexts are published.

In the context of Knowledge Graphs, a vocabulary defines a set of entity types and their property names.

The most common vocabulary used in the WWW is is an organization founded by large search engines. Its purpose is to standardize a vocabulary for information retrieval from web pages.

Rich Results

As the goal of optimization for the knowledge graph is to trigger rich results 2, you want to give priority to the subset of's vocabulary that is documented by Google.

That does not mean you should only use these entity types or properties. Because additional structured data will help Google's Search to understand the semantics of your webpage.


  1. A knowledge graph is a graph that expresses knowledge in its simplest form.

  2. Rich Results are Google features of the Search Engine Results Page (SERP)