Thermodynamics is the science behind heat and temperature and is essential to multiple disciplines such as chemistry and engineering. The initial driving force behind the study of thermodynamics was to make steam engines more efficient.  If learning about thermodynamics makes you feel warm and fuzzy there are some great links below to explore.

What is Thermodynamics?
The Three Laws of Thermodynamics
Energy, Enthalpy, and the First Law of Thermodynamics
Thermodynamics