There are two “flavors” of ligature: Standard and Discretionary. Standard ligatures (sometimes called Common Ligatures) are generally on by default, while discretionary ligatures must be turned on by the designer — they’re often historical or stylistic, instead of being necessitated by letterform incompatibility.

As you type in almost any professional text typeface nowadays, you’ll find standard ligatures automatically switching out as you go! Almost all of AF’s ligatures are standard.

Numeral Styles

Many text typefaces have multiple styles of numerals or figures. The numerals we use most often fall into two categories: Lining figures are the same height as capital letters. Oldstyle figures are usually roughly the same height and proportions as lowercase letters.

Why these different heights? Because when you’re using lining figures in inline text, it can sometimes feel like they’re shouting. They’re the same height as capital letters, so their voice is louder than the rest of the paragraph.

They also often come in two different sets of spacing. Proportional spacing means that the numerals are spaced like letters, based on the shape and width of the numeral. Tabular spacing means that the numerals all share the same width, which is necessary for applications like annual reports, where numerals all have to line up in perfect columns.

You can see this at work in the example (Wiblz Serif).

As a rule, use proportional spacing all the time, unless you’re creating something that really needs columns of numbers. Use oldstyle numerals predominantly in paragraph text.

True Small Caps

Small caps have a similar function to oldstyle numerals — they’re capital letters built to the height of the lowercase. They were created for inline use, when regular caps might seem too shouty. (You’ll notice that in long-form text, like novels, words in all caps are usually really in all small caps!

They can also be great in title or heading applications, because their different proportions add variety and stability to the text.

But beware! Unless the font actually has small capitals built into it, many typesetting applications will artificially create fake small caps by reducing the capital letter size to about 70 percent! This results in small caps that look thinner than the rest of the type, as in the example (Mr Chips).

Stylistic Alternates
& Stylistic Sets

Sometimes, for whatever reason, you may need or want multiple versions of a particular letterform. To accommodate that, many typefaces have Stylistic Alternates.

If the type designer decides that they want to group like stylistic alternates together as a set to be applied to text wholesale, they may include one or more stylistic sets.

Stylistic sets may be large or small, depending on the number of glyphs needed to create a particular look.

In the example here, some of the stylistic sets were created so that designers could choose a different standard form of ordinary letters (Mr Chips) or a different structure (Donovan Display) or a different historical feel (Pawl).

Swash Capitals

Some typefaces — particularly display scripts of all styles (including Italics) have swash capitals: a set of nonstandard capital letters that are wildly ornate compared to the rest of the typeface.

Swash caps are great when you want to give your design a little extra something, especially when it’s in a context that supports a little whimsy — invitations, diplomas, posters, you name it…

These are some examples of letterforms with and without swash caps. Top to bottom: Donovan Display, Last Midnight, Grande Jatte, and Bex Script.

Automatic Fractions

Some typefaces (usually text ones) feature automatic fractions, so if you type any number followed by a slash and then another number, the fraction will automatically be formatted correctly. Example: Mimolette.