Classes in Object Oriented Systems are continuously subjected to changes and defect prone. Predicting such classes is a key research area in the field of software engineering. It is important to identify such change prone classes and defect prone classes. Identifying change prone classes can help developers to build quality software on time. Considering all the above issues, this paper covers the following key issues: 1) identification of change prone classes using various approaches 2) How changes in one class affects multiple classes associated with it. 3) Study Dependency between classes and their effects.