This is a digression into why the layers that I am talking about in this video series are not related to "layer 2 solutions" like Polygon and Binance Smart Chain. Instead I'm talking about layers in the same manner as the upper layers of the OSI seven layer model.  I find it odd that "layer 2" solutions use the word "layer", because they don't really sit on top of the base blockchain that they use for anchoring (i.e. the Ethereum blockchain). Instead they kind of sit beside it, with bridges in order to transfer assets from Ethereum onto these sidechains.  You see, there already was a word that worked -  sidechains. I guess it didn't pass muster with the marketing people. Or perhaps you can explain to me why we need to use the term "layer 2" instead of sidechain for things like xDai or Polygon, because it's not obvious to me.