ELI5: Explain Like I'm 5

Well-order

Well-order is when you have a long list of things and you put them in a special order so that there is always a first thing on the list. It's like lining up your toys from your favorite to your least favorite. No matter how many toys you have, there will always be one toy at the very beginning of the line.

This "special order" is called a well-order, and it helps us to organize things and understand them better. For example, in mathematics, we use well-orders to study complex structures such as sets and their properties.

When we have a set of objects and we apply a well-ordering to them, we can always find the smallest object in that set, and know that it's the first one in the well-ordering. An example of a well-ordered set is the set of natural numbers {1, 2, 3, 4, ...}. The number 1 is the smallest number in this set, and is the first in the well-ordering!

In summary, well-order is a way of organizing things in a specific order from the beginning to the end, with a well-defined first element. It helps us to analyze and understand structures and sets better.