pipping is when the chick starts to make it's first pip or hole in the egg.Usually on the 20th day, you will hear the chick peep and attempt to break from the shell . He uses the tip of his beak, known as the shell tooth, to start on the inside of the egg until you sometimes see the tip of his beak peck out from a tiny crack. sometimes several hours before it hatches. it will start from that point, and the chick turns in the shell, will pip completely around or until the top half of the egg breaks loose and he pushes it off, which is sometimes referred to as zipping.good luck and happy hatching
Sorry Lilbizzy- I sent my reply before I noticed you had already replied. You did a better job of explaining it in a shorter answer.
