An **object-relational database** or ORD is a [[Relational Database|relational database]] that uses an [[Object-Oriented Database|object-oriented database]] model: objects, classes and inheritance is supported in the schema and query language; but also supports the extension of the data model with custom data types and methods like typical [[Relational Database|relational databases]]. Object-relational databases still tend to use a super-set of [[SQL]] as its main expression language, but are a perfect fit for using [[Object-Relational Mapping]] (ORM) interfaces in other languages. The most widely used ORD is [[PostgreSQL]].