US vexillologist Whitney Smith coined the term in the late 1950s.
He used it to describe the scientific study of flags – their types, forms, history, symbolism and functions – and the development of a body of related knowledge, theories and principles.
However, its meaning has since expanded to include any interest in flags more generally.
By extension, a student of flags is a vexillologist.
The art of flag design is vexillography, while a flag designer is a vexillographer.