The Delphi programming language favors an object-oriented approach, tied with a visual development style. This is where Delphi shines, and we will cover component-based and visual development in this book; however, I want to underline the fact that many of Delphi's ready-to-use features come from its run-time library (RTL). This is a large collection of functions you can use to perform simple tasks, as well as some complex ones, within your Pascal code. (I use "Pascal" here, because the run-time library primarily contains procedures and functions written with the traditional language constructs and not the OOP extensions added to the language by Borland.)
There is a second reason to devote this chapter of the book to the run-time library: Delphi 6 saw a large number of enhancements to this area, and a few more are provided in Delphi 7. New groups of functions are available, functions have been moved to new units, and other elements have changed, creating a few incompatibilities with older code from which you might be porting your projects. So, even if you've used past versions of Delphi and feel confident with the RTL, you should still read at least portions of this chapter.