Blame your phone or PC, it seems that however you're viewing this decides the font.

The actual reason requires us to go back through history and the changing of writing from Trajan to Times through Rustic, Uncial, Caroline, Protogothic, and Humanist.

Note the progression of ‘i’ and ‘l’ from ‘I’ and ‘L’ from Trajan to Rustic and then Uncial. The evolution of the Latin script culminated into the humanist minuscule

As you can see from the ‘l’ in the first row, the humanist letter starts with a diagonal stroke to the left at the top, and then a vertical downstroke which ends in a curved terminal. Or alternatively, one would start with a downstroke to the right to make a tilted rectangle, and then the downstroke which ends in a curve.

The humanist minuscule is crucial when it comes to answering this question, as it is the script on which all serif typefaces—and by extension sans-serif typefaces as well—are based.

Now we jump all the way to the late 18th century, when sans-serif lettering was first used on building facades . Or perhaps rather, the early 19th century, when the first sans-serif typeface emerged in print. Have a look at the revival Caslon Egyptian, based on Caslon’s Two Lines Egyptian from around 181.

Caslon’s Egyptian is what ultimately became known as a grotesque typeface (later also grotesk, after German), which is a class of low-contrast sans-serif typefaces. With the serifs removed and the weight contrast lowered, sans-serif typefaces embody a sense of minimalism. In Caslon Egyptian, some texture remains, such as in the spur of ‘a’ (which is often absent in later sans-serif typefaces) and the sharp terminal ending of ‘r’, but the design is a lot more minimal, and the curved terminal of ‘l’ is gone.

Along with that sense of minimalism, the ascenders of b/d/h/k/l are the same height as capital letters, and as such, there is virtually no distinction between l and uI.

But this is not always the case. As with these two archetypal minimalist sans-serif typefaces, Neue Helvetica and Futura.

As you can see, in (Neue) Helvetica the ascenders and capital letters are the same height, while in Futura—similarly to serif typefaces—ascenders are taller than capital letters.

And some typefaces, like Meta, still retain the curved tail on the ‘l’ in order to distinguish between l and uI. The increased distinction between letters improves what is called legibility, which is the ease at which letters can be distinguished from each other, which in turn improves readability.

A grotesk typeface is always going to be lower in legibility than a humanist typeface; even though Graphik does distinguish between l and uI when it comes to the height of letters, it still retains a minimalist design and texture, unlike Meta Headline, which is high in legibility but has a more unruly texture.

There are no hard rules when it comes to which typefaces differentiate between l and uI however. As you can see the word ‘Ill’ (ill) in Univers (grotesk), Founders Grotesk (grotesk), Nobel (geometric), Fedra Sans (humanist), Basic Gothic (gothic), Geogrotesque (grotesk).

While some geometric typefaces—like Futura—feature taller ascenders than capital letters, this is not the case in other typefaces, like Nobel, which is based on Futura. Also, while it is very common for humanist sans-serif typefaces—such as Fedra Sans—to differentiate between ascending letters and capital letters, it is less common for gothic typefaces (the American grotesk variant) or grotesk typefaces, and yet differentiation can be seen in Basic Gothic and Geogrotesque as well.

But it should be noted that even those typefaces that seemingly don’t differentiate between l and uI, generally actually do. When a typeface is done right, usually the capital letters are slightly thicker.

All this really proves is that Serif fonts are better then sans-serif.

Now if you lasted this long, one good for you I'm actually kinda shocked you're here, also that The Knot let's me write this much, second, here's a fun comic https://xkcd.com/1105/

Registry