An attribute domain is like a group of words that are allowed to sit in a certain category. Think of it like toys in a toy box. Just like how some toys are only allowed to be in the toy box and not in the kitchen or bathroom, some words can only be in certain categories like names, colors or sizes. This helps keep things organized so we can easily find what we are looking for. Attribute domains are used in computer programs to make sure that data is put into the right category and it can be easily sorted and searched later.