Apostrophe vs Single Quotation Mark
Two different marks that share a keyboard key and point in different directions.
The apostrophe (') and the closing single quotation mark (') are the same glyph in Unicode, U+2019, but the opening single quotation mark (') is a different character, U+2018, and it curls the other way. Confusing them produces the most common typographic error in published prose.
The failure case is a word that begins with an omitted letter: 'twas, 'em, rock 'n' roll, the '90s. Word processors see the leading mark and insert an opening quote, giving 'twas and the '90s — visibly wrong to any typographer.
The fix is to insert U+2019 directly (on many systems Alt+0146 or a text-replacement snippet), or to type a dummy character before the apostrophe and delete it afterwards so autocorrect chooses the closing form.
Common mistake: assuming the reader will not notice. Reversed apostrophes in dates and elided words are one of the fastest signals that text was not professionally set.
“Correct: the '90s, 'twas, rock 'n' roll. Wrong: the '90s, 'twas.”
Keep reading the glossary
The curled apostrophe (’) used in typeset text, as opposed to the straight foot-mark (').
Curly typographic quote marks ('smart') versus the vertical marks of typewriters and code ('straight').
The straight vertical marks (′ and ″) that denote feet, inches, minutes, and seconds — often confused with quotation marks.
The habit of typing vertical quote characters where typographic curly quotes belong.