An object that wraps a row in a database table or view, encapsulates the database access, and adds domain logic on that data.
—Martin Fowler, Patterns of Enterprise Architecture
The Active Record pattern, identified by Martin Fowler in his seminal work, Patterns of Enterprise Architecture, maps one domain class to one database table, and one instance of that class to each row of that database. It is a simple approach that, while not perfectly applicable in all cases, provides a powerful framework for database access and object persistence in your application.
The Rails Active Record framework is an implementation of the pattern and includes mechanisms for representing models and their relationships, CRUD ...