What Does Object-Oriented Database (OODB) Mean?
An object-oriented database is a database that subscribes to a model with information represented by objects. Object-oriented databases are a niche offering in the relational database management system (RDBMS) field and are not as successful or well-known as mainstream database engines.
Techopedia Explains Object-Oriented Database (OODB)
As the name implies, the main feature of object-oriented databases is allowing the definition of objects, which are different from normal database objects. Objects, in an object-oriented database, reference the ability to develop a product, then define and name it. The object can then be referenced, or called later, as a unit without having to go into its complexities. This is very similar to objects used in object-oriented programming.
A real-life parallel to objects is a car engine. It is composed of several parts: the main cylinder block, the exhaust system, intake manifold and so on. Each of these is a standalone component; but when machined and bolted into one object, they are now collectively referred to as an engine. Similarly, when programming one can define several components, such as a vertical line intersecting a perpendicular horizontal line while both lines have a graded measurement. This object can then be collectively labeled a graph. When utilizing the ability to plot components, there is no need to first define a graph; but rather the instance of the created graph can be called.
Examples of object-oriented database engines include db4o, Smalltalk and Cache.