Vexillography

Vexillography is the art and practice of designing flags; it is allied with vexillology, the scholarly study of flags, but is not synonymous with that discipline. A person who designs flags is a vexillographer.
Background of flag design.
Flag designs exhibit a number of regularities, arising from a variety of practical concerns, historical circumstances, and cultural prescriptions that have shaped and continue to shape their evolution.
Vexillographers face the necessity for the design to be manufactured (and often mass-produced) into or onto a piece of cloth, which will subsequently be hoisted aloft in the outdoors to represent an organization, individual, idea, or group. In this respect, flag design departs considerably from logo design: logos are predominantly still images suitable for reading off a page, screen, or billboard; while flags are alternately draped and fluttering images - visible from a variety of distances and angles (including the reverse). The prevalence of simple bold colors and shapes in flag design attests to these practical issues.
Flag design has a history, and new designs often refer back to previous designs, effectively quoting, elaborating, or commenting upon them. Families of current flags may derive from a few common ancestors - as in the cases of the Pan-African colours, the Pan-Arab colors, the Pan-Slavic colors, the Nordic Cross flag and the Ottoman flag.
Certain cultures prescribe the proper design of their own flags, through heraldic or other authoritative systems. Prescription may be based on religious principles: see, for example, Islamic flags. Vexillographers have begun to articulate design principles, such as those jointly published by the North American Vexillological Association and the Flag Institute in their "Guiding Principles of Flag Design".
Principles of design.
In 2006, the North American Vexillological Association published a booklet titled "Good Flag, Bad Flag" to aid those wishing to design or re-design a flag. The booklet lists five basic flag design principles which have become a standard reference in the vexillographer community. In 2014, the North American Vexillological Association, alongside the Flag Institute created an updated booklet titled "The Commission's Report on the Guiding Principles of Flag Design", which addresses issues present in "Good Flag, Bad Flag", and goes more in-depth on the ideas laid forth in the aforementioned booklet. The guidelines in this booklet can be summarized as follows: