Stateful Inspection is a network security technique used by firewalls to monitor the state of active connections. Unlike simple packet filtering, it keeps track of the state of each connection, allowing it to make more informed decisions about which packets to allow or block. This means that it can recognize whether a packet is part of an established connection or a new request. By maintaining a table of active connections, Stateful Inspection can provide better security and performance. It can identify and block unauthorized access attempts while allowing legitimate traffic to flow freely. This method enhances the overall security of a network by ensuring that only valid packets are processed.