What is a Clone? How are they made? Is cloning a good thing?

Clones are people that look alike but inside their body they are different. They don't have the same type of thinking as us. Like some of their cells are the same but they aren't the same as us still. They die earlier and its easier for them to catch diseases that make them sick. Also, they are made by taking the cells out of the same animal people want to clone but only some parts and then you just clone them. Cloning sometimes is good because if something bad happens they can catch the other one except for you. But normally its bad because it creates and adds another population into the world.