The Concept of Graph

A graph is a collection of nodes (entities) and relationships (edges) connecting them. This schema-free structure can model virtually anything: Social networks, supply chains, road systems, etc.

For example, a social network where users follow each other:

graph LR
    A -->|FOLLOWS| B
    B -->|FOLLOWS| A
    C -->|FOLLOWS| A
    C -->|FOLLOWS| B

Relationships carry semantic meaning - we can immediately see who follows whom and whether it’s mutual.

Graphs can also mix entity types. For instance, adding posts to a user node as a linked list:

graph TD
    A -->|LATEST| Post_3
    Post_3 -->|PREV| Post_2
    Post_2 -->|PREV| Post_1

LATEST points to the most recent post & PREV chains form a timeline.

Different concerns (social connections + content) coexist naturally in the same graph.