A carburetor is a device that blends air and fuel for an internal combustion engine. It was invented by Karl Benz before 1885 and patented in 1886. It is colloquially called a carb in North America.
The word carburetor comes from the French carbure, meaning 'carbide' To carburete means to combine with carbon. In fuel chemistry, the term has the more specific meaning of increasing the carbon (and therefore energy) content of a fuel by mixing it with a volatile hydrocarbon.
A carburetor basically consists of an open pipe, a "throat" or "barrel" through which the air passes into the inlet manifold of the engine. The pipe is in the form of a venturi: it narrows in section and then widens again, causing the airflow to increase in speed in the narrowest part.