Why Do Drill Bits Have Flutes?

The reason for the flutes is that drilling creates waste material, which has to go somewhere. (Its more common trade name is “swarf”). Therefore the flutes are there as the escape path for the swarf. This is why it is recommended that when you drill wholes deeper than about half a centimeter, withdraw the drill now and then to clear the swarf away. This will help to prevent clogging, overheating and various potential resulting damage.

For the same reason, never drill deeper than the drill flutes, because there will be no room for the waste material to escape, and you could damage both the tool and the project.