What's the deal with functional components in Vue.js?

I have spent a few days trying to wrap my head around functional components in Vue.js. Perhaps for someone with a React or Angular background, they are a familiar pattern, but I found that answers to even some basic questions, such as: What are functional components?Why should I care?When should I use them?proved a bit elusive. So, I spent a lot of time on this page of the Vue docs and a few other