ELI5: Explain Like I'm 5

Block (data storage)

Block (data storage) is like a big shelf where you can store lots of information. When you store something on the shelf, it is called 'saving a block'. Every block that you save is put into its own little container, like a box. Then these little containers are all stored together on the shelf. This makes it easy to find what you saved in the past, because each block is like a different box on the shelf. If you ever need to look for something again, you can easily find the block you stored it in.