It defines the fundamental physical quantities that are characterize thermodynamic systems..
it has 3 laws
1st law states that the change in internal energy of a system is equal to the sum of the heat added to the system and work it done.
2nd states that the heat cannot be transferred from a colder to a hotter body within a system without net changes occuring in other bodies within that system.
while 3rd states that it is impossible to reduce the temperature of a system to absolute zero in a finite number of steps..
there is also the zeroth law of thermodynamics taht if the two bodies are each in thermal equilibrium with a 3rd body then the frst two bodies are in thermal equilibrium with each other..
yun lang pooo :)