Stands for "Maximum Transmission Unit." MTU is a networking term that defines the largest packet size that can be sent over a network connection. The MTU is typically limited by the type of connection, but may sometimes be adjusted in a computer's network settings. Because a higher MTU allows for more data to be transferred at once, connections with high MTUs typically have more bandwidth than connections with lower MTUs.
For example, the MTU of an Ethernet connection is 1500 bytes. If a system sends packets over an Ethernet network that are larger than 1500 bytes, the data will be fragmented into smaller packets. These packets will then need to be reassembled on the receiving computer. Fortunately, the receiving computer does this automatically. However, it may cause a slowdown in the overall data transfer. Since the majority of computers connected to the Internet go through an Ethernet connection at some point, most computers have a default MTU setting of 1500 bytes.