Communication through exchange of letters is known as correspondence. We communicate our feelings, thoughts, etc. to our friends and relatives through letters that are called personal correspondence. A businessman also writes and receives letters in his day-to-day transactions. They are called business correspondence. Business correspondence or business letter is a written communication between two parties. Businessmen may write letters to suppliers of goods and also receive letters from the suppliers. Customers may write letters to businessmen seeking information about availability of goods, price, quality, sample, etc. or place an order for purchase of goods. Let us learn the details about some important business letters. The Enquiry (Inquiry) Letter. You send an inquiry when you wish to have some information on a product or its sale (after you have seen the product advertised, or displayed at a fair or exhibition, or you have only heard about it The Quotation Letter (a reply to the enquiry)– is a short letter enclosing the required catalogues and price-lists, a brochure, etc. Some 'sales talk', such as 'We are sure our high-quality products will meet your requirements, and we are looking forward to your early order' is generally included. The Letter of Complaint is sent by the customer when after receiving the goods he finds that they are not up to order. They may be of the wrong size or colour, their quality might be inferior, there might be a shortage of quantity or weight, etc. When you have a complaint, you relay this information in a professional and ethical manner to the person you have the problem with. The Letter of Apology is a reply to the letter of complaint. The Letter of Apology should be courteous, even if the complainant has abused you. You should be truthful – if you have already been having trouble with the product, say so. Try to sound sincere, and, where necessary, be prepared to take full responsibility