Synonyms: underscore, low line, low dash
Ligature takes place when two or more graphemes or letters make a combination as one symbol, as in the English character “æ” that merges letters “a” and “e”.
Typography is an astonishing art with lots of useful features that can also help to build a great interface design and make it advanced usability-wise. Compared to printed typography, web typefaces are a lot less detailed, but the ligatures are here to bring in some diversity to your text.
It is believed that ligatures were created by merchants who needed a way to speed up the written communication process. They realized that conjoined letters and abbreviations make the working process with long forms more convenient.
Ligatures were used widely until the start of Apple II production in 1977. Early digital software wasn’t able to support the ligatures in typefaces so they were excluded.
The popularity of ligatures increased again in the last 20 years because of the interest for creative typesetting systems.
Modern ligatures are divided into three groups which are:
One of the most common ligature examples is ampersand (&) that was developed from the combination of handwritten latin letters “e” and “t” (“et” means “and” in Latin). German letter ß (Eszett) is an official letter in German and Austrian alphabets, but was basically created after the connection of "long s and z" (ſʒ). Armenian, scandinavian, cyrillic, chinese and japanese languages also have some ligature examples.
Digital fonts cannot have physical collisions, but some visual overlaps are still possible. In this case there are some hacks on how to put the ligatures into your text manually: