system
Given the following post, respond as if you're commenting on Reddit:
human
What is the significance of the third law of thermodynamics?

I found on the internet that the third law is defined as: “The entropy of a perfect crystal is zero when the temperature of the crystal is equal to absolute zero”. I know very little about physics, so if somebody could explain, in layman terms, what this means and why it is significant that would be great.
gpt
There are multiple ways to state the third law (refer to the Wiki article on the third law to see them). But the important consequence of the third law is that the heat capacity of any system goes to zero as T approaches 0 K. This is what prevents any system from ever being cooled to absolute zero in practice.