Vexillology

Vexillology is the study of flags. The word comes from both the Latin word "vexilla" "little sail" for flag plus the Greek suffix"-ology" that means "study of". The "vexillum" was a particular kind of flag used by the Roman legions. Vexillology is a kind of study of symbols related to heraldry. A person who studies flags is a "vexillologist", and a person who designs flags is a "vexillographer".
Because they are flown outside, where they move with the wind, flags are usually designed with bold images and bright, basic colors. Flag design also follows a historical process, where later flag designs are based on earlier flag designs. This means that many flags in an area may look similar because they are all based on one historical flag. Examples include the Pan-African colors, Pan-Arab colors, and the Nordic Cross.
Flag Identification System (FIS).
The "Flag Identification System" was created by Whitney Smith and adopted by Fédération internationale des associations vexillologiques (FIAV).
The first row is for use on land and the second row is for use on water, each divided into private (civil), government (state), and military (war) use.
There are 63 symbols that can describe the flag, including:
Other symbols are used to describe other uses of the flag, such as official status and which side of the flag is shown. The symbols in common use are: