Cordless drill features: Electric brake.
Electric brake is drill feature which helps you to stop the spinning bit.
Once you stop holding the power trigger the braking will start so the drill stops rapidly permitting you to put the drill down more safely, otherwise you run off time when waiting for the spinning bit to stop before you can put it down. Before electric brake system masses became impatient and place the drill down while it was spinning down and this was an unsafe practice and was the case of injuries where the spinning bit got caught on the cable and cause electrocution or caught something else which spun the drill causing the bit your enter the persons arm or hand causing physical damage.
The feature description taken from here
Related posts:
Cordless drill features: Chuck size
