When talking about objects, we often shorten "this object is an instance of the class User" to "this is a User." As far as we're concerned, both sentences mean the same thing and the phrase "is a" is equivalent to "instance of".
What's more, Ruby actually gives us a method called just that. Let's look at an example.
As you've probably guessed,
Object#is_a? accepts a single parameter - a class.
Object#is_a? has an alias,
Object#kind_of?. They're identical in every respect so you're free to pick whichever reads better in a given context.
Here's an exercise that requires you to combine
Object#is_a? with something you've already learned about classes. As always, your objective is to make the tests pass.