Area element

Imagine you have a toy farm with a large grassy field. Now, imagine you need to know how much grass is in that field. To do that, you can break the field up into smaller pieces, called squares. Each square has an area, which is how much space it takes up.

An area element is like one of those squares, but it can be any shape, not just a square. It's still a little piece of a larger area that we're trying to measure.

For example, if we're trying to measure the area of a circle, we can break it up into a bunch of tiny "slices" that are like pizza wedges. Each slice is an area element, and they all add up to the total area of the circle.

So basically, an area element is just a small piece of a bigger area that we can measure and add up to figure out the total area.