In modern usage, civil engineering is a broad field of engineering that deals with the planning, construction, and maintenance of fixed structures, or public works, as they related to earth, water, or civilization and their processes. Most civil engineering today deals with roads, structures, water supply, sewer, flood control and traffic.
Engineering has developed from observations of the ways natural and constructed systems react and from the development of empirical equations that provide bases for design. Civil engineering is the broadest of the engineering fields. In fact engineering was once divided into only two fields--military and civil. All the engineering specialties have derived from civil engineering. Civil engineering is still an umbrella field comprised of many related specialities.
Source: Wikipedia
