Object-oriented development is a partial-lifecycle software development method in which the decomposition of a system is based upon the concept of an object. This method is fundamentally different from traditional functional approaches to design and serves to help manage the complexity of massive software-intensive systems. The author examines the process of object-oriented development as well as the influences upon this approach from advances in abstraction mechanisms, programming languages, and hardware. The concept of an object is central to object-oriented development and so the properties of an object are discussed. The mapping of object-oriented techniques to Ada using a design case study is considered.