Me too. And what makes it extra confusing? The fact that different style guides recommend capitalizing different words. Let’s review one of the big guys: Associated Press, also known as AP style.
This style likes more caps than the other major styles. Like most style guides, they recommend only “important words” get capitalized, an ambiguous term that drives me crazy. That means that whether a mouse is on a table, at a table, or in a table is of no importance because on, in, and at are all prepositions. Which brings me to my first rule:
Lowercase any preposition of less than four letters.
Don’t know what a preposition is? Typically, they denote the physical place of something in relation to something else: in, on, by, at, under, with, and over are common ones. But there really are so many–and so many words with multiple functions–that if you’re unsure, look the word up in the dictionary.
Lowercase any conjunctions of less than four letters.
Common conjunctions include for, and, nor, but, or, and yet.
Then there’s “sentence case.”
This is exactly what it sounds like–capitalize the same way you would in a sentence: first words get capitalized as well as any proper nouns. Simple as that. Unfortunately, it doesn’t seem as relevant as regular title capitalization nor will it win you any grammar brownie points.
Capitalize the articles a, an, and the if they’re either the first or last word in the title.
Otherwise leave them lowercase.
Capitalize the first word in a sub-title.
This is usually the first word after the colon.
Need some examples? I’ve got a few:
Rogue One: A Star Wars Story
Manchester by the Sea
Kubo and the Two Strings
Never Let Me Go
The Fault in Our Stars
Kafka on the Shore