Block are one of the most important and most used features of Ruby.
A hash is an unordered, dictionary-like collection of pairs of keys and values.
An array is an ordered collection of objects; they can be of any type and you can intermix different types inside a particular array.
Explore functions in Ruby, how to create and use them. And understand why there are no Ruby functions 🤓
This topic is purely "academic" - global variables should never be used.
Class variables are used for data that is associated with the class rather than the instances of that class.
Everything in Ruby is an object and classes are the blueprints from which objects are created.
How to destructure arrays and objects.