= Active Record -- Object-relational mapping put on rails

Active Record connects classes to relational database tables to establish an
almost zero-configuration persistence layer for applications. The library
provides a base class that, when subclassed, sets up a mapping between the new
class and an existing table in the database. In context of an application,
these classes are commonly referred to as *models*. Models can also be
connected to other models; this is done by defining *associations*.

This is for Ruby on Rails 6.1.