Low Extra Delay Background Transport (LEDBAT) is a way to transfer data on the Internet quickly without clogging the network.
[5] At one point in time, LEDBAT was estimated to carry 13–20% of Internet traffic.
[4][6][3] LEDBAT is a delay-based congestion control algorithm that uses all the available bandwidth while limiting the increase in delay;[2][7] it does so by measuring one-way delay and using changes in the measurements to limit congestion that the LEDBAT flow itself induces in the network.
LEDBAT congestion control has the following goals:[2] The two main implementations are uTP by BitTorrent and as part of TCP by Apple.
[8] Apple uses LEDBAT for Software Updates so that large software downloads to macOS computers and iOS devices do not interfere with normal user activities; Apple also makes the source code available.