This technical brief examines the underlying technologies used in Web 2.0 applications. It also explains how Web 2.0 introduces some daunting security challenges. New application coding hazards produced by Web 2.0 can elevate the risk of cross-site scripting (XSS) injections, cross-site request forgery (CSRF), unauthorized access, and other Web-based attacks. Lastly, this brief illustrates a number of defense strategies that businesses can use to safely roll out Web 2.0 applications, including application development best practices and dedicated Web application security solutions.