Turning both directions while drifting

hey so im new to the community and in all of the fastest times on the TT leaderboards have people who start their drift in one direction but are able to turn both directions mid drift (for example holding a drift to the left but still being able to turn the kart to the right during the drift). im prob just out of the loop but if someone could explain what that actually is to me that would be greatly appreciated.

Reverse drifting. Using the back button you can reverse your direction