A letterform is the shape that defines each letter of the alphabet. Each letter is generally identified by its individual appearance as well as various other components and characteristics. These identifying aspects are seen in letters written or printed on paper, portrayed on a computer screen, or carved in rock by ancient cultures. Different parts of letters make up the overall structure, while the height of each is defined by appropriate terms as well. Additional lines called serifs, at the tops and bottoms of some forms of typography, are one aspect of letterform that has been used throughout history.
Typeface without serifs has been used since the early 1900s. Some people believe that serifs make reading more convenient, but they are generally not necessary unless the letterform is etched into metal or stone. Text printed on computer screens typically does not have such small details like serifs; online print is generally 12 pixels in height, so these would ordinarily not be visible.
Ascenders are lines that project upward in a letterform, while descenders point downward. Crossbars are often used to connect lines as in a capital A. The top of a lower case f, for example, is called a terminal. Other common terms for a letterform also include a shoulder, the curve of a lower case n; and a counter, the open space within an area enclosed by solid lines as in the letter O. A curved line that encloses this space is called a bowl.
The height of a letterform can also be analyzed. A mean line is often used to represent the space where most of the letters in a word or phrase is contained. The baseline indicates the bottom of letters not accounting for descending lines; the minimum extent of these is shown as the lowest extent of the descenders. Height limits for capital letters, ascenders, and the vertical extent of the letter X, if it is present, are denoted as well.
Variant methods of writing can make a letterform appear much different. Calligraphy is the artistic representation of letters, which can be drawn by hand to take on shapes that often do not fit the standard rules for typeface. The letterform is often studied in paleography, the study of ancient forms of writing, and epigraphy, the study of engravings in materials such, as stone and metal, which were often created by ancient civilizations.