Horizontal datum

Ok kiddo, imagine you have a big ball. It's called the Earth. People need to know where things are on the Earth so they can find them and go there. But imagine every single person had their own way of saying where things are and it was different from everyone else! That would be really confusing, right?

That's why we have something called a "horizontal datum." It's like a special way of saying where things are on the Earth that everyone agreed on so we can all be on the same page.

It's kind of like a big grid that covers the Earth. This grid is like a big piece of paper that we use to draw on so we can mark where everything is. This grid has lines that go up and down (we call them "longitude") and lines that go side to side (we call them "latitude").

Using this grid, we can say exactly where something is on the Earth. For example, if you wanted to find the Empire State Building in New York City, you could say it's at latitude 40.7484° N and longitude 73.9857° W. That means it's a certain distance up and down and a certain distance left and right from a certain point on the Earth.

So, a horizontal datum is just a special way to use this grid to say where things are on the Earth. It helps us all talk about where things are in the same way so we don't get lost or confused. Cool, huh?