Creating Magento extensions can be an extremely challenging and time-consuming task depending on several factors such as your knowledge of Magento internals, overall development skills, and the complexity of the extension functionality itself. Having a deep insight into Magento internals, its structure, and accompanying tips and tricks will provide you with a strong foundation for clean and unobtrusive Magento extension development.
The word unobtrusive should be a constant thought throughout your entire development process. The reason is simple; given the massiveness of the Magento platform, it is way too easy to build extensions that clash with other third-party extensions. This is usually a beginner's flaw, which we will hopefully avoid once we have finished reading this book. The examples listed in this book are targeted toward Magento Community Edition 184.108.40.206. Version 220.127.116.11 is the last stable release at the time of writing.
You can download the full installation archive from the official Magento site at http://www.magentocommerce.com. You might need to register as a user on a site in order to initiate the download.