What tool is specifically required to cut internal threads in a hole?

To cut internal threads in a hole, a tap is specifically required. Taps are designed to create a screw thread on the inside of a hole, allowing for the insertion of screws or bolts that can be securely fastened. The cutting edges of a tap remove material as it is turned, forming precise threads that match standard screw sizes.

This makes taps essential for applications where components need to be fastened together securely. Unlike the other tools mentioned, a drill is used to create holes without any threading, a chaser is used for external threads, and a reamer is meant to enlarge or finish existing holes rather than create threads. Thus, the tap is the appropriate tool for achieving internal threads effectively.