First law of thermodynamics
In internal energy of a system the change is the total heat transferred to or from the system & the work done on or by the system.
Second law of thermodynamics
The entropy is a measure of the unavailability of a system's energy to do useful work of a closed system tends to enhance with time.
Third law of thermodynamics
For changes including only perfect crystalline solids at absolute zero, the change in the over all entropy is zero.