The simplest method is wrapping a piece of tape around the drill bit. Once the tape reaches the surface, the user stops drilling.
It is quick and inexpensive, but it is still based on visual judgment. The tape can also move or become difficult to see when chips and dust build up.
A drill stop collar provides a more mechanical solution. The collar is fixed around the drill bit at a selected position and contacts the workpiece when the target depth is reached.
This can work well for repetitive jobs, but the collar must be positioned correctly and tightened securely. On some drill bits, it may also interfere with chip removal or shift during use.
A drill press uses a different approach. Instead of attaching something directly to the bit, the machine limits the downward travel of the spindle. This provides more repeatable depth control, but it requires a stationary setup.