The book declared that all of us who have completed the course this far have been promoted to Intermediate Programmer. There is nothing that illustrates the difference between the "Hello World" level of programming and higher levels of ability more than understanding how to work with Arrays and Collections. There is a huge world of tricks and techniques that we can use once we understand this key part of VB.NET.
The subtitle of this lesson, "the next best thing to a database" is actually only partly true. You can get a real feeling for what a database does by studying how arrays and collections are used, but they're really targeted at different requirements. A database is for storing huge amounts of information where the relationships between things are critical. If "automobile" is one type of data in the database and "person" is another, then "person owns automobile" is a relationship. That kind of thing would be difficult to do with arrays and collections.
While reading this chapter, you might want to remember the things that were covered in Chapter 7, Using Loops and Timers. The main reason for using arrays and collections is to use iterative processing with them, that is, process them with various types of program loops. (The book covers a new one, For Each, that is designed just for collections.)
