on The Book Designer:

In my article last month, Amazon is a Search Engine–Make Your Book an Easy-to-Find Product, I explained that the first concept is to think about Amazon as a search engine, instead of a retail store. Today, I will be discussing the second concept and why you should think of Amazon as a data gathering and filtering tool.

Amazon is a sophisticated and intelligent software system that not only stores a large catalog of products that users can search for, but also stores a lot of sales and buyer preference information, too. Like some fictional electronic big-brother, Amazon watches what you do and records it so that it can find ways to recommend a product that you might want to buy. It does its job really well and is getting smarter with each upgrade.

So, what does Amazon watch you might ask?