In typography, the various portions of a type character, which include:
The apexThe top junction of two stems, such as the point of the capital "A" or the center of the capital "W." The opposite of an apex—or the bottom junction of two stems—is the vortex. The capital "W" has one apex and two vortex points. The inside of an apex or a vortex is known as a crotch.
The counter is the fully or partially enclosed part of a letter, as in the lowercase "e," which has a full counter above and a partial counter below. The term counter refers to the space itself, while the term bowl refers to the lines enclosing the counter. The proportion of the counter to the character is important to legibility. A complete bowl is formed by curved strokes only, and a modified bowl has the stem forming one of the sides. A loop is a bowl that serves as a flourish, as in the descending part of some lowercase "g" characters.
The stem is the main vertical stroke or principal stroke in an oblique character or face and is the dominant element in most characters. Elements that are perpendicular to the stem or connected to it or to other main parts of the letter include the arm (a horizontal or diagonal stroke starting from the stem, as in the capital "E" or "F"), the bar (an arm connected on both sides, as in the capital "H"), the crossbar (a horizontal stroke that crosses through the stem, as in the lowercase "t"; the capital "T" stroke is more accurately two arms), the ear (a short stroke extending from the bowl of a lowercase "g" or from the stem of a lowercase "r"), the tail (a downward-sloping short stroke, ending free), the beak (the outer portion of arms and serifs of the letters "E," "F," "G," "T," and "Z'), the arc (any curved stroke that is not a bowl), and the spine (the main curved arc section of the letter "S").
A terminal is a free-ending stroke of a letter, commonly with some kind of special treatment, which can be acute (having the angle of an acute accent), concave (rounded out), convex (rounded in), flared (extended), grave (having the angle of a grave accent), hook (looped), pointed (coming to a point), sheared (sliced off), straight (even with the stroke itself), or tapered (graduated). A type of terminal is the finial, a more decorative, alternative ending to a stroke, such as a ball (having a rounded shape), barb (the end of an arc), beak (commonly a half-serif"]), or a swash (a flourish).
The variations of these letter elements are what distinguish one typeface from another.