Datagram Transport Layer Security - Definition from the Hotspot Shield Glossary
DTLS is a communication protocol that is used as a security measure to ensure messages and data cannot be tampered with, forged, or communications cannot be eavesdropped on.
The protocol is based on the TLS protocol (Transport Layer Security) and is a derivative of SSL - It improves upon SSL by the fact that it can create a secure protocol under UDP (User Datagram Protocol). DTLS is solely used for datagram based applications. DTLS is useful when there is a delay in the transmission of data for example in VPN’s and other tunneling applications. Datagram Transport layer Security is defined by the IETF in RFC 4347.