Appendix A. Active Model API Reference
Active Model is a Rails library containing various modules used in developing frameworks that need to interact with the Rails Action Pack library. This came about by extracting common functionality that was not persistence specific out of Active Record, so that 3rd party libraries did not have to copy code from Rails or monkey patch helpers in order to conform to the API.
Out of this extraction came extremely useful reusable functionality to developers of Rails compatible libraries, such as dirty attributes, validations, and serialization into JSON or XML. And simply by using these modules developers could be DRY and not need to rewrite what has already been done before.
Section headings reflect the name ...