SCTP stands for Stream Control Transmission Protocol.

SCTP as a protocol can be seen as a hybrid of UDP and TCP.

At its core, SCTP holds the following characteristics:

• Connection oriented. Similar to TCP, SCTP is connection oriented. It also offers a multi-homing capability that isn’t used by WebRTC
• Optional reliability. Reliability is optional in SCTP and is up to the implementer using SCTP to decide if he needs this capability or not
• Optional ordering. Ordering of packets sent via SCTP is optional and is left for the implementer to decide if this is necessary for him or not
• Message oriented. SCTP makes sure that each message sent is properly parsed on the receiver end in the same manner in which it was sent
• Flow control. Similar to TCP, SCTP provides a flow control mechanism that makes sure the network doesn’t get congested

SCTP is not implemented by all operating systems. In such cases, an application level implementation of SCTP will usually be used.

SCTP is used in WebRTC for the implementation and delivery of the Data Channel.

Google is experimenting with the QUIC protocol as a future replacement to SCTP.