Layer by layer

"Layer by layer" means building something by putting one piece on top of another. Imagine you are building a tower out of blocks. First, you take one block and put it on the ground. That's the first layer. Then, you take another block and put it on top of the first one. That's the second layer. You keep doing this until your tower is as tall as you want it to be. Just like your tower, some things are created by building them layer by layer, adding one piece at a time until it's finished!