Knowledge Graph

A knowledge graph is a graph1 that expresses knowledge2 in its simplest form. This simple form is the expression subject-predicate-object. For example, "John knows Jane".

A knowledge graph consists of:

Entities are the nodes in the graph. They are unique and have an identity.

Properties are specific attributes with a value. Each property is assigned to an entity.

Relations are those properties where the object is another entity. For example, "Bob's father (a person) is Mike (another person)". Relations are the edges of the graph.

Entities with the same set of properties (predicates) are of the same entity type3.


  1. A graph is a network of nodes and edges. An edge describes a relation between nodes.

  2. Knowledge is information, facts, information, or skills. People acquire knowledge through education or experience.

  3. An entity type describes a class of entities with the same set of (potential properties). For example, a person has a name and a birthday.