QSFP stands for "Quad Small Form-factor Pluggable." It is a compact, hot-pluggable transceiver module used for high-speed network connections, typically in data center and telecommunications applications. The "quad" in QSFP refers to its four-channel design, which allows for higher data transmission rates by using multiple lanes. QSFP modules are commonly used for 40 Gigabit Ethernet (40GbE) and 100 Gigabit Ethernet (100GbE) connections, but there are also variations like QSFP+ and QSFP28 that support different data rates.