Flags often inherit traits seen in traditional European heraldry designs and as a result patterns often share names.
Flag illustrations generally depict flags flying from the observer's point of view from left to right, the view known as the obverse (or "front"); the other side is the reverse (or "back"). There are some exceptions, notably some Islamic flags inscribed in Arabic, which is written from right to left; for these the obverse is defined as the side with the hoist to the observer's right.
A vexillological symbol is used by vexillologists to indicate certain characteristics of national flags, such as where they are used, who uses them, and what they look like. The set of symbols described in this article are known as international flag identification symbols, which were devised by Whitney Smith.