ELI5: Explain Like I'm 5

Flood fill

Have you ever tried painting a picture and accidentally spilled some paint outside of the lines? It can be frustrating to try to clean it up without ruining the rest of the picture. This is where flood fill comes in!

Imagine you have a coloring book page with lots of different shapes that are outlined, but not yet colored in. Now, imagine someone gave you a special marker that, when you tap it inside one of the shapes, will automatically fill in that entire shape with the same color. That's what flood fill does!

In computer programming, flood fill is a technique used to "color in" or "paint" a specific area of a digital image or graphic interface. It starts at a chosen point, usually one that is already colored, and then "spills" that color outwards until it hits the boundaries of the area it is supposed to color in.

Think of it like a paint bucket in a digital art program. You select a color, click on a specific area, and watch as the program automatically fills that area with that color. But with flood fill, you don't have to click on each little section - it automatically detects the boundary and fills it all in for you.

This technique can be used in many different ways, such as filling in the background of a photo or coloring in different sections of a game board. It saves a lot of time and hassle by automatically filling in large areas with just a few clicks.