- SQL (Structured Query Language) based databases
- MySQL, PostgreSQL, …
- Has a fixed schema, which can be modified later but requires downtime. So, careful schema design is required beforehand
- Easily vertically scalable - more entities can be added. Horizontal scaling (adding more attributes to entities) is hard, requires complex Sharding
- Reliable
- Relational databases are great for transactional data
- ACID compliant
- reduces anomalies