The 7 Cs of business writing are: 1. Completeness - Answer all questions fully using the 5Ws and 1H. 2. Conciseness - Be focused and avoid unnecessary words. 3. Consideration - Focus on the reader's needs and use a positive tone. 4. Clarity - Use simple, familiar language and effective structure. 5. Concreteness - Provide specific details, facts, and vivid descriptions. 6. Courtesy - Be sincere, tactful and avoid language that could offend. 7. Correctness - Ensure accurate information and proper writing mechanics.