We have nothing in our everyday experience that says that there is any lower bound to temperature. We might imagine that if we kept a perfect refrigerator running and running the temperature would just get lower and lower. Well, it doesn't. There is an absolute minimum of temperature and we first see how that came about when we look at Charles' law. We all know that if things get cold, then shrink.
Gasses are an even better example of that.
The exact relationship can be studied with something a simple as air, but it works for all gasses. If you raise or lower the temperate of a fixed amount of air at fixed pressure the volume increase and decreases linearly with temperature. If you change gasses so pure nitrogen or helium, the same thing happens. What we learn from Fig. 2 is that if you plot the volume of a gas against temperature, it looks like a straight line for all gasses.