This document summarizes a talk on add-on development for ExpressionEngine. It discusses the three types of add-ons in EE - extensions, modules, and plugins. It covers important skills for add-on development like PHP, SQL, HTML/CSS, and JavaScript. It provides guidance on developing add-ons including researching existing approaches, mapping out features, designing database structures and template tags, and building the control panel. The document emphasizes best practices like following EllisLab development guidelines, proper commenting, sanitizing inputs, and using abstraction.