The business letter consists of 7 parts: 1) letterhead with company information, 2) date, 3) recipient's name and address, 4) salutation like "Dear Sir", 5) message/body, 6) complimentary closing like "Yours faithfully", and 7) the writer's signature without title. The letterhead establishes the company's identity. Dates, names, addresses, and titles should be correctly formatted. The message should clearly state the purpose and be concise using short paragraphs and sentences.