[Thumper1960]

Lock out, tag out refers to disabling power to equipment and locking the power panel or disconnect and red tagging it so no one may operate it or “accidentally” energize the panel or equipment. The keys are kept by the crew or person doing the work on the equipment.

[right way right]

On top of locking and tagging the actual equipment, there is often a collective point where every employee working who is any where near the project has a pad lock with their name attached to it locked to a gathering point. (Often just a board with holes to attach locks)
Each employee is responsible for their own lock and key.
If a lock with a tag is present on that collection point it is always presumed that that individual is still in the danger area and absolutely nothing is to operate until that person is found and removes their own lock. There is no mercy for the continued employment of one who forgets to grab their labeled lock before they go home. You can call them at home even and talk to them but the machine is not to be operated until they remove the lock with their own hands.