Lowercase refers to the smaller form of letters in the alphabet, as opposed to uppercase, which are the larger, capital letters. For example, the lowercase version of the letter "A" is "a." Lowercase letters are commonly used in writing and are essential for proper grammar and sentence structure. In typography, lowercase letters are often used for readability and to create a more casual tone in text. They are typically used in the body of written content, while uppercase letters are reserved for specific purposes, such as the beginning of sentences or proper nouns like John or Paris.