Apple Corer is a hand-operated tool designed to facilitate removing the cores from apples.
It gives you apples ready to bake as they are or ready to slice into perfect rings, etc
It has a handle at one end, and at the other, a sharp round ring of metal that you press down through the centre of the apple.
You press the metal ring through an apple, starting at the top, until the ring comes out through the bottom, then pull and twist it back through. The core gets caught in the Corer and pulled out with it.
Some won’t have gougers wide enough to take out the whole core in one go, depending on the size of your apple. You may have to take a second pass at the apple.
Some but not all are dishwasher safe.
You can also use an Apple Corer for pears.
You don’t have to peel or cut the apple first: you can start with a whole, unpeeled apple, Wash the apple first, though: whatever might be on the outside, you are about to press down into your apple.