Egg poachers let you cook eggs without standing over them and carefully monitoring their progress. This is really helpful in the morning if you're on a tight schedule or have lots of kids to get out of the house for the school bus. An egg poacher also ensures that your eggs are poached just right every time.
There are both electric and microwave egg cookers. Many of the egg poachers will also let you boil eggs in the shell as well. Most of the egg poachers work on the same principle. You take the egg out of the shell and put it in one of the egg compartments. The cooking time is controlled by the amount of water you put in the egg poacher. The water amounts are clearly spelled out in the eggs poacher instructions.