Speedlites: High Speed Sync

Canon calls this feature Focal Plane (FP) Mode.

High Speed Sync is part of the E-TTL feature set firing at rates of up to 1/8000. A few companies have found a way to achieve such rates without E-TTL by implementing Hyper Sync, Super Sync or Overdrive Sync, which basically means the flash being fired too early at a more standard rate and thus reaching full power in time, when the shutter opens. Some of those even offer manual fine tuning of the forerun.