Object-Oriented Modeling, or OOM, (Object Oriented Programming - OOP)is a modeling paradigm mainly used in computer programming. Prior to the rise of OOM, the dominant paradigm was procedural programming, which emphasized the use of discreet reusable code blocks that could stand on their own, take variables, perform a function on them, and return values.

The Object-Oriented paradigm assists the programmer to address the complexity of a problem domain by considering the problem not as a set of functions that can be performed but primarily as a set of related, interacting Objects. The modeling task then is specifying, for a specific context, those Objects (or the Class the Objects belongs to), their respective set of Properties and Methods, shared by all Objects members of the Class. For more discussion, see Object-oriented analysis and design and Object-oriented programming. The description of these Objects is a Schema.

As an example, in a model of a Payroll System, a Company is an Object. An Employee is another Object. Employment is a Relationship or Association. An Employee Class (or Object for simplicity) has Attributes like Name, Birthdate, etc. The Association itself may be considered as an Object, having Attributes, or Qualifiers like Position, etc. An Employee Method may be Promote, Raise, etc.

The Model description or Schema may grow in complexity to require a Notation. Many notations have been proposed, based on different paradigms, diverged, and