Typography 101 – Character Make-Up

There is quite a lot of terminology associated with the make-up of a character. There are specific names for certain arcs, joins, apexes and appendages, but for most of your career you may not need to know many of these. Indeed, some of them would only really be pertinent to a conversation between two typographers actually designing a typeface from scratch, so I won’t go into them in this article. However, there are some quite important names given to key aspects of a typeface’s make-up and its measurement system that all designers should know by heart.

X-height
The x-height is actually quite self explanatory. It refers to the height of the lower case x within a typeface. This is important as it usually typifies the height of the main portion of the entire alphabet.

Ascenders & Descenders
The ascender is the portion of the characters of the alphabet that protrude above the x-height. Examples are lower case characters like; d, l, b, h and k. The height defined by the top of the ascender is often referred to as the Cap Height. While this is reasonably close to the truth, the Cap Height is usually a little lower than the Ascender Height. Many newer typefaces however unify these heights to a single line. The term Cap Height is more commonly used in this case.

Conversely, descenders are the portion of a character that hangs below the ‘baseline’ or the invisible line that text rests on. Examples are lower case characters like; p, y and g.

The point size of a typeface is calculated by measuring the height from the bottom of the descender to the top of the ascender.

Serifs
The terms serif and sans-serif refer to the portion of some styles of typeface which adhere to old aesthetic conventions. The serif of a letterform is the pronounced protrusion at the top and bottom or more generally the end of a straight line within a character. This is the oldest style of typography, referred to as Old Style or less commonly Humanist, and dates back to the 1400s. For further reading I have written a small article specifically on the chronological styles of typography.

Points & Picas
The measurement system for typography is in Points and Picas. These measurements are absolute measurements. This is because they relate to the physical units of inches. The units break up as follows: One inch is equal to 72 points or 6 picas. This means there are 12 points in a pica. It is worthwhile noting that in web design, when working at 72dpi, 1 point is equal to 1 pixel, so web designers can use these terms interchangeably.

Another way of measuring type in a relative way is by using ‘em’ and ‘en’ units. The em square is supposed to be the square that is created by drawing a box around a lower case m for any given typeface.

This measurement is always the point size of the typeface and is also equal to an ‘em dash’. Half an em square or em dash is an en square or an en dash. All these measurements are relative to the typeface and size you are using and have no direct link to a physical size.
This makes the use of the em as the unit of typographic and relational measurement on the internet a perfect solution. If the user decides to resize a page of text that has been designed and built using em units as its measurement and layout system, the entire page should reflow maintaining all relative positions, leading and kerning etc.