Neo4j

Neo4j is a graph database management system designed to store and query highly interconnected data. It uses a graph data model in which data is represented as nodes connected by relationships, with properties on both nodes and relationships. This labeled property graph model supports complex networks such as social graphs, IT topologies, and knowledge graphs.

The database uses the Cypher query language, a declarative syntax for expressing graph patterns. Cypher enables pattern matching, filtering, aggregation, and updates. Neo4j also supports the openCypher standard to align with other implementations.

Neo4j is ACID-compliant and transactional. It provides indexing, constraints, and full-text search. The platform offers high availability through clustering in its Enterprise edition and in cloud deployments, including Neo4j Aura. A Community Edition provides core graph database capabilities.

Architecturally, Neo4j stores data in a native graph format optimized for traversals and rapid joins. It exposes language drivers (Java, Python, JavaScript, .NET, and more) and APIs for integration. The ecosystem includes data import/export tools, visualization, and monitoring utilities.

Common use cases include social networks, fraud detection, real-time recommendations, IT operations, and knowledge graphs. Neo4j competes with other graph databases and, in some scenarios, with relational systems when queries emphasize deep relationships.