In typography, a ligature refers to a specially designed character created by connecting or combining two or more characters into one. This is done for one of two reasons: to improve the look of characters that crash, collide or combine in an unattractive way (referred to as standard ligatures), or to offer a more decorative option to the standard characters (referred to as discretionary ligatures, as they are used at your discretion).
The most common standard ligatures are the f-ligatures: fi, fl, and occasionally ff, ffi, and ffl. These designed letter combinations remedy the unattractive collision that can occur in some typefaces between the hook or crossbar of the f and the dot of the i, or other elements of its neighboring character.
The standard ligatures found in Adobe Jenson stylishly solve the problem of character pairs and triplets that collide or combine unattractively.
Jenson Italic’s double f ligatures contain elegant, staggered alignments, typical of many historic typefaces.
Other standard ligatures found in some fonts include fb, ffb, fj, ffj, fk, ffk, ft, fft (many of which are common in other languages) as well as Th. Some calligraphic fonts contain numerous “non-standard” standard ligatures designed to imitate the natural joins and overall flow of hand-written text.
Caflish Script Pro contains numerous two-, three-, and even a four-letter standard ligatures, all intended to create a natural look that imitates the flow and spontaneous joins of handwriting.
Keep in mind that while it is an accepted practice to always use standard ligatures in running text, it is not typographically “mandatory”, but rather a determination that you can make with consideration for the typeface in use, and your personal preferences. Although ligatures can improve the rhythm and flow of many classic typefaces in both roman and italic versions, other typeface designs—including many sans serifs—look good either with or without them.
Some typefaces, especially sans serifs, look good with or without the use of standard ligatures; it is more a question of personal taste. Which setting do you prefer in these examples set without and with f-ligatures? Set in Tangent, Soho Gothic, and Harmonia Sans.
Discretionary ligatures are more decorative in nature, and are an option when seeking variation from the default characters. They can be historic, ornamental, elegant, or just plain fun. Common discretionary ligatures are ck, sp, st, rt, as well as other historical forms, including many long s ligatures (these look like a lowercase f with a shortened or nonexistent right crossbar), not to be confused with standard f ligatures. Although occasionally found in some Type 1 and TrueType fonts, discretionary ligatures are more common in newer OpenType fonts due to their expanded character capacity.
The use of discretionary ligatures can add personality, individuality, and flair to an otherwise unadorned setting, as illustrated in these examples of ITC Avant Garde Gothic (upper) and Expo Serif.
Properly designed ligatures should match the spacing of the rest of the font. If they appear too tight or open when placed next the neighboring characters, they will stand out and disturb the overall color, texture, and rhythm of the text. Note that text whose spacing has been altered with the tracking feature available in most design software can result in ligatures appearing too open or too tight next to surrounding text.
Locating and Accessing Ligatures
OpenType fonts, with their expanded character capacity, can contain an unlimited number of both standard and discretionary ligatures. Older Type 1 and TrueType fonts typically only have room for fi and fl ligatures. If you’re using Adobe InDesign, the best way to see which ligatures are available in a font is by using the Glyphs panel. OpenType fonts will usually have a Standard Ligature subset, as well as a Discretionary Ligatures subset if the font contains any. Older font formats will not have these subsets, so to see any available ligatures, choose Entire Font from the Show menu in the Glyphs panel.
You can view an OpenType font’s standard and discretionary ligatures by choosing them from the Glyphs panel’s Show menu, as illustrated above. To view ligatures in older font formats, choose Entire Font.
ITC Avant Garde Gothic has hundreds of discretionary ligatures—many more than your average font.
Once located, ligatures can be accessed one of two ways: either manually/individually by inserting the cursor in the text and double-clicking on the desired ligature in the Glyphs panel; or globally, by selecting text and enabling (Standard) Ligatures and/or Discretionary Ligatures from the Character or Control panel menus.
Standard ligatures are generally considered to be typographically desirable, especially in running text, and therefore are commonly turned on by default in most design software. When using InDesign, they can easily be turned off from the Character panel (center). Discretionary ligatures, conversely, are inactive by default, but can be activated from the OpenType submenu (right).
Some fonts and foundries categorize the historic long s ligatures (highlighted in green) as standard, rather than discretionary. Don’t confuse or interchange them with the f ligatures, as they are totally different characters, and their use would result in a virtual misspelling of the word.
InDesign can also apply ligatures via paragraph and character styles. In the Style Options dialog boxes, you can find the controls for standard ligatures in Basic Character Formats, and discretionary ligatures in OpenType Features.