Obverse and its opposite, reverse, refer to the two flat faces of coins and some other two-sided objects, including paper money, flags, seals, medals, drawings, old master prints and other works of art, and printed fabrics. In this usage, obverse means the front face of the object and reverse means the back face. The obverse of a coin is commonly called heads, because it often depicts the head of a prominent person, and the reverse tails.
In fields of scholarship outside numismatics, the term front is more commonly used than obverse, while usage of reverse is widespread.
In publishing, "recto" and "verso" are used for the front and back of pages in books, especially manuscripts, meaning the first side of a leaf encountered by a reader, which will be on the right of an opening for Western manuscripts, but on the left of an opening for those in many Asian and Middle Eastern languages such as Chinese and Arabic. For prints and drawings with material on both sides the one judged as more significant will be the recto.
Generally, if in doubt, the side of a coin with the larger-scale image will be called the obverse (especially if the image is a single head) and, if that does not serve to distinguish them, the side that is more typical of a wide range of coins from that location will be called the obverse. A convention now exists typically to display the obverse to the left (or above) and the reverse to the right (or below) in photographs and museum displays, but this is not invariably observed.