Following up on another post, I’d like to provide some information on when special typographic symbols should be used.

• Ampersand (&) — Used informally to denote “and”
• Ampersat (@) — Commonly used in email address but also used informally to denote “at” or, in healthcare, “before”
• Asterisk (*) — Denotes a footnote; also used to indicate unknown letters (as in “sh*t”)
• Asterism (⁂) — Rarely used symbol that calls attention to text that follows
• Back slash (\) — Used primarily in computing and website addresses
• Caret (^) — Commonly used by editors and copyeditors to indicate text or other content to be added to a particular location in a document
• Copyright (©) — Used to indicate a copyrighted name or document, typically immediately prior to the copyright year
• Dagger (†) — Also called an obelisk; denotes a second footnote (double dagger ‡ ) on a page
• Degree (°) — Indicates degrees of temperature or angle
• Zero glyph () — Infrequently used in typography; used in handwriting to indicate zero as distinguished from capital O
• Ellipsis (…) — Indicates missing text (Note: When an ellipsis is used at the end of a sentence (use an ellipsis symbol and then a period.)
• Em dash (—) — Commonly used to replace a colon, comma, or parenthetical phrase (Called “em” dash because it is the width of the lowercase “m”)
• En dash (–) — Indicates a range, as in 2–4 or 2007–2010; also used as a minus sign (Equal to ½ width of em dash)
• Guillemets () — Used in some languages to indicate speech
• Hyphen (-) — Used to join words (“full-blown argument”) or indicate a missing word (“short- and long-range” )
• Interpunct (ᐧ) — Rarely used dot between words; sometimes used in logos
• Interrobang (‽) — Rarely used combination of exclamation point and question mark; indicates an exclamatory question (“Do you have any idea what you’re doing‽”)
• Lozenge (⧫) — Open or closed diamond often used as a bullet
• Pound sign (#) — Also called octothorpe or hashtag; indicates pounds in weight or to precede a word or phrase (without spaces) commonly searched online
• Obelus (÷) — Division sign in mathematics
• Pilcrow (❡) — Commonly used by editors and copyeditors to indicate new paragraph break
• Prime (′) — Used most often to indicate feet or minutes; double prime used to indicate inches or seconds
• Registered trademark (®) — Indicates name or logo that has been registered with a national trademark office
• Section sign (§) — Also called silcow; most commonly indicates a particular section of a document, especially legal documents
• Virgule( ⁄) — Also called solidus; separates nominator and denominator in a fraction; not the same as a forward slash, which is more upright (/)
• Therefore sign (∴) — Used in mathematical proofs before a logical consequence
• Tilde (~) — Used as a diacritical mark over letters (ã) or in mathematics to indicate an approximation (~18) or similarity between values
• Trademark (™) — Used after a symbol, word, or phrase legally representing a company or product of a company