Web Application Firewall protects Web sites and Web applications from attackers who exploit vulnerabilities applications or protocols to steal data or to change the appearance of the organization's website. Protects against denial of service attacks (Denial of Service, DoS). Unlike traditional network firewalls or penetration detection systems (IDS), which just released an HTTP, HTTPS or FTP traffic to Web Applications, Web Application Firewall acts as a proxy of the two-way traffic. Checks if the operation does not attack, isolated web servers from direct access by hackers. In addition, Web Application Firewall eliminates attacks carried out by deliberate change issues applications (eg disables editing cookies). Unlike penetration detection systems that analyze only bit sample Web Application Firewall takes over the whole operation instead of the web server. Decodes communication and removes invalid characters or issues and normalizing data. Further systems allow protection against misuse of sensitive data.