What is the difference between trap messages and inform messages for SNMP?

Inform messages differ from trap messages with respect to acknowledgment. Trap messages employ a best effort delivery utilizing UDP. Inform messages employ acknowledgments; while they use the User Datagram Protocol (UDP), they rely on the Application layer for acknowledgments. Trap messages are not always encrypted and can be sent with plaintext. Inform messages use acknowledgments at the Application layer. Trap messages do not use acknowledgments.