Vexillology is the scientific study of the history, symbolism and usage of flags or, by extension, any interest in flags in general. The word is a synthesis of the Latin word vexillum ("flag") and the Greek suffix -logia ("study.") The constitution of the International Federation of Vexillological Associations (known by its French acronym, FIAV) formally defines vexillology as "the creation and development of a body of knowledge about flags of all types, their forms and functions, and of scientific theories and principles based on that knowledge."
A person who studies flags is a vexillologist; vexillography is the art of designing flags; one who does so is a vexillographer; an admirer of flags is a vexillophile.
The study of flags, or vexillology, was formalized by the U.S. scholar and student of flags Whitney Smith in 1957. He then moved to organize various flag organizations and meetings including the first International Congress of Vexillology, the North American Vexillological Association, and International Federation of Vexillological Associations. The term was conceived in 1958 by Smith. It has historically and appropriately been considered a sub-discipline of heraldry.
Since 1965, an International Congress of Vexillology (ICV) has been organized every two years under the auspices of FIAV. The 2015 ICV was in Sydney, Australia.