One of the most pronounced shortcomings in those who write today lies without any doubt in the poor or erroneous use of punctuation marks. Punctuation marks modulate the message, emphasize or attenuate ideas and content, and determine the musicality of the prose. In short, an incorrect or inappropriate use of them can make a brilliant text turn into an almost unreadable mess, or just the opposite. The result is an essential work in the library of any self-respecting writer.