Building Blocks: understanding the layers of blockchain technology

All good things have layers. There are layers in good food, layers in good clothing and layers in good technology.  Take for example a mobile phone. Here we have mobile networks, physical mobile devices, different operating systems and then the different apps available on the operating system. Each of these parts of a phone are layers: The network is Layer 1; the Operating system is Layer 2; and then App stores/apps are Layers 2/3.