Chicago style capitalizes "Is" but lowercases "of" — so the correct title case of the story is over is The Story Is Over, not The Story is Over. Most people reach for a "capitalize any word longer than three letters" shortcut, and it gets this exact phrase wrong: "is" is short but it's a verb, so it goes up; "the" is short and an article, so it stays down. Case rules are fussier than they look, and the fussiness is where the embarrassing mistakes live — usually in a headline or a slide title where everyone can see them.
The five cases worth knowing
Five styles cover almost everything you'll ever type:
- UPPERCASE — every letter capital:
ANNUAL REPORT. Loud. Good for short labels and acronyms, risky for anything longer. - lowercase — no capitals at all:
annual report. Common in casual messages, some brand wordmarks, and code. - Sentence case — capitalize the first letter and any proper nouns, nothing else:
Our annual report is ready. The Guardian uses it for headlines, and most modern app interfaces default to it. - Title Case — capitalize the major words:
Our Annual Report Is Ready. Standard for book titles, article headlines, and formal headings. - camelCase / snake_case — the machine-safe code cases, covered below.
Two of these cause nearly all the trouble: Title Case, because the rules are subtler than they appear, and UPPERCASE, because it carries a tone you often don't mean to send.
How title case actually works
Title case goes by a word's grammatical job, not its length. Capitalize nouns, verbs, adjectives, adverbs, and pronouns. Lowercase the small connective words: articles (a, an, the), coordinating conjunctions (and, but, or, nor), and short prepositions (of, to, in, on, at, by, for).
Then the exception that trips everyone: always capitalize the first and last word, whatever it is. So "Something to Talk About" capitalizes "About" — a preposition you'd normally lowercase — because it's last. And "The Fault in Our Stars" keeps "The" capitalized because it leads.
Worked example. Take a river runs through it, word by word: "A" (article, but first word → up), "River" (noun → up), "Runs" (verb → up), "Through" (preposition longer than four letters, which most guides cap → up), "It" (pronoun and last word → up). Result: A River Runs Through It. Now the taming of the shrew: "The" (first → up), "Taming" (noun → up), "of" (short preposition → down), "the" (article, mid-title → down), "Shrew" (noun and last → up). Result: The Taming of the Shrew.
Style guides disagree at the edges — AP capitalizes prepositions of four or more letters; Chicago lowercases prepositions regardless of length. If you're writing for a specific publication, follow theirs. For everyday headings, the part-of-speech rule plus the first/last exception gets you right nearly every time.
When ALL CAPS reads as shouting
Online, a sentence in ALL CAPS reads as yelling — a norm that goes back to Usenet and BBS boards in the 1980s. Send a coworker "PLEASE SEND THE FILE" and, whatever you meant, it lands as an order barked across the room.
There's a legibility cost too. All-caps text strips out the ascenders and descenders — the stems on the b, d, p, q — that we use to recognize word shapes at a glance. Miles Tinker's mid-century readability studies found continuous all-caps passages read meaningfully slower than mixed case, on the order of 10 percent over longer stretches. That's fine for a three-word button or a logo, and punishing for a paragraph.
Use UPPERCASE deliberately: short labels, table headers, acronyms, a single word of emphasis. For anything a person actually has to read, mixed case wins on both tone and speed.
camelCase, snake_case, and the code cases
Programmers need machine-safe names with no spaces, and each language has house rules:
- camelCase — first word lowercase, each following word capitalized:
userName,getElementById. JavaScript variables and functions. - PascalCase (UpperCamelCase) — every word capitalized:
UserName,HttpClient. Classes and React components. - snake_case — all lowercase, words joined by underscores:
user_name. Python and Ruby variables, most SQL columns. - SCREAMING_SNAKE_CASE — all uppercase with underscores:
MAX_RETRIES. Constants in most languages. - kebab-case — lowercase with hyphens:
user-profile. URLs, CSS classes, HTML attributes.
Mixing these inside one codebase is a real source of bugs. A Python function named getUserData reads as foreign in a file full of snake_case, and an API that returns user_id in one endpoint and userId in another will burn someone an afternoon.
Fixing case without retyping it
The usual reason people ask about case is that they've already typed something in the wrong one — Caps Lock was on, a title came in lowercase from a spreadsheet, a list of names arrived shouting. You don't retype it.
The built-in tools are close but flawed. Word's Shift+F3 cycles a selection through UPPERCASE, lowercase, and Capitalize Each Word — but "Capitalize Each Word" capitalizes every word, so "the lord of the rings" becomes "The Lord Of The Rings," with "Of" and "The" wrongly raised. Excel's =PROPER() has the identical flaw: =PROPER("war and peace") returns "War And Peace." Neither knows real title-case rules.
A dedicated converter that follows the article/preposition rule handles that correctly, and usually offers sentence case and the code cases in the same click. Everyboringtool's Case Converter does the conversion in your browser — nothing is uploaded and there's no sign-up — which matters when the text is a client roster, a contract clause, or anything you'd rather not paste into someone else's server. Paste, pick the case, copy back.
When changing case is the wrong move
Automatic conversion is dumb about names. It doesn't know "iPhone," "eBay," "McDonald," "iOS," or "PhD" carry internal capitals, and it can't tell "IBM" is an acronym that should stay whole. Run "IBM announced iOS support" through a sentence-case pass and you can get "Ibm announced ios support." So after any bulk conversion, eyeball the proper nouns, brand names, and acronyms and fix them by hand — the machine gets the grammar words right and the identity words wrong.
Two more limits. If you're writing to a publication's style guide, a generic title-case tool won't match their preposition rule — use their standard, not a default. And never run a converter over live source code to rename things: changing a variable's case in a text tool changes one copy of the word and silently breaks every reference to it. Use your editor's rename-refactor for that. Converting a snippet to coin a new name is fine; converting code in place is not.
Keep two rules in your head and you'll rarely be wrong: title case goes by part of speech, not word length, and the first and last words are always capitalized. For everything else, don't retype — cycle it with Shift+F3, clean up Excel's PROPER over-capitalization by hand, or paste into a converter that offers real title case and does the work locally. Then give proper nouns one last look before you send.