Candling allows you to see inside the egg to see the development of the chick inside. I use a super bright LED torch and a toilet roll [with paper on it] to balance the egg on and focus the light beam through the egg.
Out of the 24 eggs I have:
1 possibly infertile
3 bloodrings [started developing but died]
1 possibly developing
A fertile and developing egg. You can see the veins and the developing chick [blob] I could actually see the little black blob moving!
An egg with a bloodring, means the egg started developing but for some reason stopped.
Another fertile egg, you can see some veins in it, but I’m not sure this one will make it to full term, as the shell’s pores are so large, but I am hoping it will.