ModSecurity is a plugin for Apache web servers that functions as a web application layer firewall. It is employed to stop attacks against script-driven websites by employing security rules that contain specific expressions. This way, the firewall can stop hacking and spamming attempts and protect even websites which aren't updated on a regular basis. For instance, numerous unsuccessful login attempts to a script admin area or attempts to execute a certain file with the purpose to get access to the script shall trigger specific rules, so ModSecurity will stop these activities the moment it detects them. The firewall is incredibly efficient because it tracks the entire HTTP traffic to a site in real time without slowing it down, so it will be able to stop an attack before any damage is done. It also keeps an exceptionally detailed log of all attack attempts that features more information than traditional Apache logs, so you could later analyze the data and take additional measures to enhance the security of your sites if necessary.