Can you name different types of databases you have worked with or are familiar with?

There are several main types of databases that are frequently used:

• Relational databases (SQL) — store data in tables with a fixed schema. Examples: PostgreSQL, MySQL, SQLite, Oracle.
• Document-oriented databases (NoSQL) — store data in document format (usually JSON-like). Examples: MongoDB, CouchDB.
• Key-Value stores — simple databases for storing key-value pairs. Examples: Redis, Riak.
• Graph databases — store data in the form of graphs (nodes and edges). Example: Neo4j.
• Column-oriented databases — optimized for analytical queries by columns. Example: Apache Cassandra.

Depending on the task, the appropriate type of database is chosen. For example, relational databases are usually used for complex transactions and strict data integrity, while NoSQL is preferred for flexible schemas and scalability.