Interpunction is a noun that refers to the insertion of a punctuation mark. 

Emerging in the mid 18th century, our word of the day comes from the Latin word punctum (POONK toom) meaning ‘point,’ the same word that gave us ‘punctuate.’ Unlike the verb punctuate, interpunction is a noun that refers to the act of adding punctuation. Here’s an example:

I’ve learned that in office memos, it is best to be careful with interpunction. Adding an explanation mark to a sentence can make you sound more angry than you intend to.