What NoSQL databases do you know?

• Document-oriented: Store data as documents (JSON, BSON, XML). Suitable for semi-structured data. Examples: MongoDB, CouchDB.
• Key-value stores: The simplest type. Data is stored as an associative array. Fast access by key. Examples: Redis, Memcached, DynamoDB (key-value mode).
• Columnar: Data is organized by columns rather than rows. Optimal for analytical queries and aggregation of large volumes of similar data. Examples: Cassandra, HBase.
• Graph: Represent data as nodes and edges (relationships). Ideal for modeling complex relationships. Examples: Neo4j, ArangoDB (graph model).
• Time series: Specialized for storing and analyzing time-dependent data. Examples: InfluxDB, TimescaleDB.

The choice depends on the nature of the data, access patterns, and scalability requirements.