Now that is an interesting question you may think and I think your answer may be uncertain.

There is actually no catch to this question, the answer is simply that a chair would not be a chair if it does not have a back and a seat.

I was also going to add four legs, but then I would not be able to include the ergonomic chairs, as they have five legs that make the chair safer to roll, as an ergonomic chair.

We know that a chair is designed for sitting, as that goes without saying; but most people are not aware that they also need to move their body while sitting, for preventing discomforts in their skeletal body.

Ah you may say, it is so difficult to move around, while you are sitting.

That is not the right answer that I want to hear!

It is easy to move around while you are sitting, all you have to do is breathe in and out; then your body is moving!

When I discuss movement, do not think of it as a physically active as walking or running. These are very physically active movements, which are deigned more for fitness than just getting you skeletal joints moving.

Movement itself can be very, very small that you can barely be aware of the actual movement, such as breathing. But if you take a deep breath, you will feel much more of your body move.

This is a good way to breathe, but not constantly; or you will do something called hyperventilate, which means that you will force too much oxygen into your body.

It means that your body will not have balanced breathing and you may faint or become dizzy with too much oxygen in your body.

However, if you don't breathe adequately, you may also faint; due to a lack of oxygen and too much carbon dioxide in your system that needs to escape.

Your body needs to be balanced in so many ways. It is in fact a very well-designed machine that is built with so many protective mechanisms for helping in survival.

A chair is therefore designed for you to sit on with comfort. But in order to maintain that comfort, your skeletal body has to make some minor movements for you to appreciate the comfort.

The movements can come from taking a deep breath now and again or moving your pelvic bones from side to side. Even giving your body a big stretch now and again will help to provide some active movement to your body, as that is really what movement is really all about.