A letter is a written message that conveys information, thoughts, or emotions from one party to another. It can be formal or informal, depending on the purpose and audience. Formal letters are used in business, legal, or official communication, while informal letters are more personal and casual. Letters can be handwritten or typed and are traditionally sent via mail, though digital formats like emails have become more common. They often follow a structured format, including a greeting, body, and closing. Despite modern advancements in communication, letters remain an essential means of conveying detailed and thoughtful messages.