Jeff opens with a bunch of computer science terms, and then goes on to illustrate how Amazon is (happily) solving technical challenges that don't have solutions, either in academia or the tech world. He describes how Amazon is using Service Oriented Architecture — basically building many things and services instead of one or a few massive applications that do everything. For example, to render a product detail page for a customer, between 200 to 300 services are needed for everything from recommendations to inventory tracking to order fulfillment. This gives the customer a highly personalized view. Jeff then goes into how Amazon is solving problems at-scale that no one else is having to solve. For the nerd crowd, this letter is really worth the read. Jeff closes out the letter tying back to free cash flows. After all this letter is for shareholders, not nerds.