What is a Kotatsu?

I am sure some of you might be wondering what a kotatsu is? You might even have been loosing sleep on it. Well, problem resolved: it is a traditional Japanese table with a heating unit onto which you put a blanket covered with a tray. It looks like a a low table with a skirt. It is used to heat the bottom part of your body in the winter so that you don't need to heat the room. You can even have a nap under it.
Wikipedia has a great article that will explain you that it is similar to a Korsi which is used in Iran.
What is the point? Well, if you have a freezing cold home like mine, it seems like a possibility of de-freezing the legs. More seriously though, it is a very efficient way of heating in winter. You don't have to heat the whole room and only the space which is closest to you; this is how despite not insulating their homes, Japan manages to use no more energy per capita than the UK. Their insulation is the blanket.
For clarity, below is a toy one which you can buy here. It even heats for real...
You can buy a "striking" real one here or even get advice to build one from an Ikea table here. What bliss.