Most countries in the world are “really metric countries”. And yes we do use the cm a lot for measurements inside the 1-100cm range.

I read all that and I must admit I am still not quite sure what part of all that is markdown, and why any of it is markdown.

I get that this sentence must be the key concept: ““Markdown” is the name of a particular standard way of formatting text so that programs can reliably interpret parts of that text as representing the writers desire for their text to be displayed a particular way.” But it reads like a tautology without really explaining either statement.