What are non-printing characters what are the different marks that writer uses for displaying nonprinting characters?

Non-printing characters are symbols that represent formatting and control functions in text but do not appear in the final printed output. Common marks used to display non-printing characters include paragraph marks (¶) for line breaks, dots (·) for spaces, and arrows (→) for tab characters. These symbols help writers and editors visualize the structure of the text, making it easier to identify formatting issues or spacing inconsistencies.