I got this book at a time when using COM with Microsoft web servers was popular (back around 2001-2003), and I saw a lot of terms thrown around that I didn't recognize. This book really helped me navigate what was going on with that world. It explained the history of the evolution of COM from the days when it was called OLE in Windows 3.0 up through COM+. In terms of Microsoft technology, COM+ was the predecessor to what Microsoft called ".Net".