Honda developed VTEC (Variable Timing and Lift Electronic Control) to improve the volumetric efficiency of a four-stroke internal combustion engine. Ikuo Kajitani, engineer at Honda was the first involved in the development of these four-valve engines. The Honda’s VTEC system uses two camshaft profiles and hydraulically selects between profiles.
VTEC system was used by Honda for good fuel economy and smooth operation of vehicle.
The VTEC Engine ~ world.honda.com
Checkout the video explains how VTEC system works