F-ligatures are special characters found in just about every professional font. A ligature is two or more characters that are combined to form a single glyph. Ligatures fall into two categories: standard and discretionary. Standard ligatures are designed to solve the problem of neighboring characters that either collide or combine in unattractive ways. Discretionary ligatures are more decorative in nature and are intended to be used at one’s discretion, thus the term discretionary. F-ligatures usually fall into the first category; they are considered to be desirable in most typesetting usages, and are therefore “turned on” by default in nearly all design software.
There can be as few as two, or as many as a dozen or more f-ligatures in a digital font. Older font formats, such as Type 1 and TrueType, only had room for the fi and fl ligature. Today’s OpenType fonts, with their greatly expanded character set, can accommodate many more, often including ff, fi, fl, ffi, ffl, and occasionally fb, ffb, fj, ffj, fk, ffk, ft, fft, fh, and ffh, some of which are more common in other languages.
Many f-ligatures are connected forms, while others are not – yet they are all designed to improve the appearance of these neighboring glyphs. Note that all digital fonts need to have something in the fi and fl position, or digital map, so even if these character combos look fine without a special ligature, they will still appear together in this location with no alteration.
F-ligatures can be found in metal type where one block of type would replace two or more, thus improving the appearance of colliding or unattractive character combinations. These corrective forms were included in the phototypesetting technology that followed metal type, as there were no limits on the number of characters. But with the onset of digital typesetting, many ligatures had to be discarded, as the earliest digital font formats (such as Type 1 and TrueType) didn’t have room for more than two ligatures. The greatly expanded OpenType font format that followed changed all that (as previously mentioned), and can include as many ligatures as the typeface designer could wish for.
The opinion commonly held by many designers is that f-ligatures are very desirable in text – especially with serif typefaces – but not always in the larger display settings. Personally, I keep the standard f-ligatures activated in all instances, but will turn them off for the occasional setting if the individual characters look better than the ligature. It is really a question of personal taste, and a decision that should be made on a case-by-case basis depending upon the font being used.
There are several situations that call for special consideration regarding the use of f-ligatures:
• Take notice of any ffi or ffl combinations when using a font that only contains the fi and fl ligatures. Sometimes the combination of the single f with the fi or fl ligature can results in an unattractive, unbalanced appearance. When this is the case, turn off the f-ligatures for these instances.
• Don’t confuse the long s ligatures with f-ligatures. The long s is an historic form that looks like an f that is missing the right side of the crossbar, resulting in a glyph that is commonly mistaken for an f. To complicate matters even more, long s ligatures are frequently grouped together with f-ligatures under the standard ligature category, making it easy to confuse them.
• Use f-ligatures with extreme care – or avoided entirely – if you plan to adjust the overall letterspacing (or tracking) of the text containing these combinations. Since a ligature is a single glyph, the spacing between the characters won’t change when the letterspacing of a word or setting is opened or tightened; this can result in uneven and inconsistent spacing between the ligatures and the rest of the text. (Note that some design software will replace ligatures at a certain tracking threshold with the single characters in order to maintain consistent spacing.)
All ligatures can be easily viewed in the Glyphs panel, especially from the Standard Ligatures submenu. As mentioned earlier, most standard ligatures are turned on by default, as can be seen with a check mark in the InDesign Character panel dropdown menu. This is also where they can be deselected. If you want to turn f-ligatures on or off on an individual basis, highlight the character(s) in question and either select or deselect “Ligatures” from this panel; a ligature can also be selected from the Glyphs panel. Note that most word processing software has ligatures turned off by default, but they can easily be turned on.