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.

Usage	Private Use	Government Use	Military Use
Land Use	Civil Flag	State Flag	War Flag
Sea Use	Civil Ensign	State Ensign	War Ensign

There are 63 symbols that can describe the flag, including:

Text mode	Description	Usage
C/*	Civil Flag	by private person on land
S/***	State Flag	by state offices on land
W/*	War Flag	by military on land (army)
*/C	Civil Ensign	on private ships (merchant ensign)
**/S*	State Ensign	on state owned ships
*/W	War Ensign	by military ships (navy)
CS/**	Civil and State Flag	by private person and state on land
SW/**	State and War Flag	by state services and military on land
CSW/***	National Flag	for all purposes on land
***/CSW	National Ensign	for all purposes on ships
CSW/CSW	National Flag and Ensign	for all purposes on land and sea

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:

Normal or de jure version of flag, or obverse (front) side
Design proposed but not officially adopted
Design is a reconstruction
Reverse (back) side of flag
Design is a variant (a different form of the same flag)
Alternative (different) version of flag
De facto (unofficial but in actual use) version of flag
Flag has different designs on its front and back
Obverse (front) side meant to be hoisted (raised) with pole on the right
Design approved by the government to represent a nation
Design used in the past, but now abandoned (This symbol was not part of Smith's original set.)
Reverse side is mirror image of obverse side
Reverse side is the obverse side flipped
Information about the reverse side is not known
Flag can be hung vertically by hoisting on a normal pole and then turning the pole 90°
Flag can be hung vertically by rotating the design first
Vertical hoist method is unknown
Design has no element that can be rotated
Flag can only be hoisted vertically