A stateful firewall monitors the state of active connections and makes decisions based on the context of the traffic. It allows traffic that is part of an established session to return through the firewall, which makes it ideal for ensuring that responses to client requests are permitted, while blocking unsolicited incoming connections. Other types of firewalls such as packet filtering and proxy firewalls do not maintain state and therefore cannot dynamically allow or deny traffic based on established connections. A web application firewall primarily focuses on HTTP/HTTPS traffic to protect web applications from security threats and would not necessarily have the capability to monitor the state of all types of network connections.