One of the most popular open source relational databases is MariaDB Server. It was created by the original MySQL developers and iit is included in most cloud services and is installed by default in most Linux variants.
In a wide range of applications, from banking to internet, MariaDB converts data into structured information. It is utilized because it is fast, scalable, and robust, with a rich ecosystem of storage engines, plugins, and many other features that make it very versatile for a wide range of use cases. It was originally created as an upgraded, drop-in replacement for MySQL.
Moreover, as an advanced database server, it supports newer SQL features like CTE (Common Table Expressions) and SQL on JSON while maintaining compatibility with commercial offerings like Oracle and MySQL.
Source: https://mariadb.org/about/
(Provigil)