Where is a cedilla or cedille used?

Question

What name is given to a special day or happening, used variously over centuries to mark important days in a calendar, to mark capitals or rubrics in religious texts, or to wear particular clothing?

Answer 1

In written Portuguese, Catalan, Occitan, and French
The cedilla is a symbol used under the letter "c", usually, in these languages to modify the sound to that of an "s". A mark similar to a cedilla is also used in Turkic and similar languages to represent the English sound "tch".