What is Vexillology?
Vexillology is the study or science of flags, or more accurately the study of the history, symbolism of flags. Usually national flags are studied in vexillology, but it can be utilised with any flags in general, like custom flags, sports flags, custom banners or others.
For example, lets take the French flag.
After the French Revolution, it was one of the first tricolor flags in Europe and the world. Most flags have many meanings. The meanings of the French tricolor stripes are, for the blue stripe: the bourgeoisie, for the white stripe: the clergy, and for the red stripe: nobility.
What about the Canadian flag?
The Maple Leaf, Red and White are the official colors of Canada proclaimed by King George in 1921. The Canadian flag symbolizes peace and honesty with white background, and hardiness, bravery, strength and valor with red stripes and maple leaf.
Those are just a few examples of historical flags and their meanings, there have been hundreds of custom flags throughout history, some that are no longer in use and most are stil in use as modern day national flags.