A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relational database systems are equipped with the option of using SQL (Structured Query Language) for querying and updating the database.
What is relational database
Relational Databases are based on relational data models designed to store data in rows & columns and in a tabular format. RDBMS is famous for its SQL (Structured Query Language), and can fit to any tech stack. RDBMS is mostly meant for transactional use cases, OLTP with the ability to process data in milliseconds. A lot of RDMBS are available like MySQL, Postgres, AuroraDB etc.