Flag of Nepal
Flags are usually rectangular in shape, but may be of any shape or size that is practical for flying. Named shapes include square (e.g., the national flag of Switzerland and the state flag of the Vatican City), pennant, double pennant (e.g., the state flag of Ohio), swallowtail, triangular or swallowtail burgee, gonfanon and oriflamme. A more unusual flag shape is that of the flag of Nepal, which is in the shape of two stacked triangles.

Often the image is through and through, in which case there are two possibilities:

>> the image is symmetric in an axis parallel to the flag pole, so the image is the same when viewed from the other side
>> when viewed from the other side one sees the mirror image; this is very common and usually not disturbing if there is no text in the flag - the whole image of flag with flag staff is not the same anyway, with the staff on the other side; examples are the flag of the United States with stars and stripes on the hoist-side, and the former Nazi swastika flag at sea (compare with the flag on land mentioned below)
If the image is not through and through there are also two possibilities:

>> the image is not symmetric, nevertheless the image is the same when viewed from the other side; for example the former Nazi swastika flag on land ([1], at the bottom)
>> the image is different; examples are the former national flag of Paraguay, the state flag of Oregon, and the now-obsolete flag of the Soviet Union.

Flag of Kiribati
Common designs on flags include crosses, stripes, and divisions of the surface, or field, into bands or quarters - patterns and principles mainly derived from heraldry. A heraldic coat of arms may also be flown as a banner of arms, as is done on both the state flag of Maryland and the flag of Kiribati. Writing occasionally features on flags – for example, on several flags of U.S. states, or on revolutionary flags of the former Soviet Union. The practice is, however, not widely favoured, as it is expensive to reproduce accurately, and is either difficult to read on the reverse of a flag (in mirror image), or sewn on both sides of the flag, making the flag too heavy to fly properly.

The flag of Libya, which consists of a rectangular field of green, is the only national flag using a single color and no design or insignia.