Extensible Threat Management (XTM) is the next generation of Unified Threat Management (UTM). Where UTM describes a category of network security appliances that integrates a range of security features such as firewall, gateway anti-virus, and intrusion detection (IDS) and prevention (IPS) capabilities; XTM expands on these security features to include better networking capabilities and management.
XTM typically includes additional security and control features for network bandwidth, traffic shaping, dynamic routing, load balancing, VPN, VoIP security and more.
See also Unified Threat Management (UTM).