What is the purpose of a subject line in a business letter?

The purpose of a subject line in a business letter is to summarize the letter's content. It serves as a concise preview of the main topic or purpose of the communication, allowing the recipient to quickly grasp the letter's intent before reading the full text. This efficiency is particularly valuable in a business context, where professionals often deal with numerous communications and need to prioritize their responses.

By clearly indicating the subject matter, the subject line helps establish the focus of the correspondence and can enhance the reader's engagement with the letter. It is not meant to confuse the reader, nor does it provide personal information about the sender, as that would detract from professional communication standards. Additionally, while the subject line sets the stage for the content of the letter, it does not serve as a closing statement, which would be found at the end of the correspondence. Therefore, a well-crafted subject line effectively summarizes and clarifies the letter's objective, making it an essential component of business writing.