QUIC is designed to work over UDP (User Datagram Protocol), which is a lightweight and connectionless protocol, unlike TCP (Transmission Control Protocol), which is a connection-oriented protocol. UDP (User Datagram Protocol) is a simple, lightweight, and connectionless protocol that does not provide many of the features that TCP (Transmission Control Protocol) offers, such as reliability, flow control, and congestion control. Unlike TCP, which sends cumulative ACKs that acknowledge all packets up to a certain point, QUIC can send selective ACKs that acknowledge specific packets, allowing the receiver to indicate which packets have been received successfully and which packets are missing.