Uppercase letters are the tall, capital forms of letters in the alphabet: A, B, C, rather than a, b, c. When you start a sentence, you use an uppercase letter. When you write someone's name, like Sarah or Toronto, the first letter is uppercase.

In writing, uppercase letters serve important purposes. They mark the beginning of sentences and show that a word is a proper noun: a specific person, place, or thing. Sometimes people write entire words in uppercase for EMPHASIS or to show someone is SHOUTING. But using too many capitals can make text hard to read and may seem like yelling.

The opposite of uppercase is lowercase. Knowing when to capitalize matters: turkey is a bird you might eat at Thanksgiving, while Turkey is a country that bridges Europe and Asia. One letter can make all the difference.