This is a relational database management system that was forked from the development of MySQL. It has largely been a drop-in replacement for MySQL, although it has acquired its own specialties.
MariaDB
Tag: RDBMS
PostgreSQL
PostgresSQL is similar to MySQL, this relational database management system strives for ACID (atomicity, consistency, isolation, durability) compliance. It also features data types for JSON, XML, key-value, and geometry.
MySQL
MySQL is a relational database management system. It is hugely popular and found in many well-known products like Facebook, YouTube and WordPress, to name a few.
MySQL had its development forked into MariaDB.