There are four main times when you'll capitalize words:
1. The First Word of a Sentence
You'll always have to capitalize the first word of a sentence:
2. People's Names and Proper Nouns
You should always capitalize names:
You should also capitalize proper nouns:
3. Capitalize the First Word of a Quote – But Only When the Quote Is a Complete Sentence
When writing a quote, you should capitalize the first word of the sentence, as long as it's complete:
You wouldn't need to capitalize the following quote:
4. Capitalize Days, Months, and Holidays
You should always capitalize the names of days, months, and holidays. You never need to capitalize the names of seasons:
What About Words in Titles?
Depending on the style guide you're following, you should capitalize most of the words in titles. Typically, articles, conjunctions, and prepositions under five letters are lowercase, while all the rest of the words are capitalized.
You should always capitalize the first word of a title, as well as the first word after a colon: