Google has published a "Browser Security Handbook" on their portal, emphasizing importance of secure design of Web applications. The handbook describes common concepts found in the most popular browsers, as well, as presents security features that are part of their implementation. This document is an important resource to those involved in Web application design and implementation. Most of us rely on frameworks and packages (like Joomla!, or phpBB) that shield us from most of the details, but it is important to understand the basic concepts and know the possible sources of security threats.