The natural sciences study the physical, nonhuman aspects of the world. As a group, the natural sciences are distinguished from the Social Sciences, on the one hand, as well as from the arts and humanities on the other.
The term natural science is also used to differentiate between "science" as a discipline following the scientific method, and "science" as a field of knowledge generally, e.g. computer science or even "the science of theology".
Natural Sciences in Wikipedia:
External Resource: The History of Recent Science and Technology (http://hrst.mit.edu/)