In this chapter, you were introduced to the various types of collections found in Immutable.js. We then looked at some code that creates new instances of these collections. Most of the time, you'll want to pass some initial data to a collection when it's created. There are a number of ways to create collections with initial data, including passing native JavaScript types to the constructors and using the of() static method. We then looked at the fromJS() function for when you need to parse complex JavaScript structures into their Immutable.js counterparts.
In the next chapter, you'll learn how to mutate your collections using persistent change methods.