Associations let us access our data in diverse and flexible ways, simplifying our queries and allow some of our CRUD functionality.
When we are creating apps we start with a map of our initial tables and build them out one at a time.
After we create a table we add any necessary associations. To get some practice, we will start by drawing an ER Diagram, determining the proper associations/relationships between models and test them out in pry.
Note: These are often questions you may get in a technical interview when it comes to modeling a database for an app.