Case styles refer to the different ways in which letters and characters are formatted in writing. Common case styles include uppercase, lowercase, title case, and sentence case. Each style serves a specific purpose, such as emphasizing text or indicating proper nouns. In programming and design, case styles also play a crucial role. For example, camelCase combines words without spaces, capitalizing the first letter of each subsequent word, while snake_case uses underscores to separate words. Choosing the appropriate case style can enhance readability and maintain consistency in written content.