An object that wraps a row in a database table or view, encapsulates the database access, and adds domain logic on that data.
For a full description see P of EAA page 160
An object carries both data and behavior. Much of this data is persistent and needs to be stored in a database. Active Record uses the most obvious approach, putting data access logic in the domain object. This way all people know how to read and write their data to and from the database.