The Object-Relational Developer's Guide gives you all the information you need to take advantage of the object-oriented features of Oracle Database.

You can use object types to follow an object-oriented paradigm for your database development. Or you can just make occasional use of object types for collection datatypes. Or you might just use some of the object types pre-defined in Oracle Database, such as those used in the spatial and graph technologies. In all of those cases, it'll come in very handy to understand the differences between static, member, map and order methods, and also how to invoke methods of supertypes from within a subtype method.