Upper case refers to the larger form of letters in the alphabet, often used to signify the beginning of sentences or proper nouns. For example, the letter "A" is an upper case letter, while "a" is its lower case counterpart. Upper case letters are typically used in titles, headings, and for emphasis in written text. In typography, upper case letters are also known as capital letters. They are essential for clarity and readability in written communication. The use of upper case can help distinguish important information, such as names of people like John Doe or places like New York City.