Business letter
（重定向自Letter of inquiry）
A business letter is usually a letter from one company to another, or between such organizations and their customers, clients and other external parties. The overall style of letter depends on the relationship between the parties concerned. Business letters can have many types of contents, for example to request direct information or action from another party, to order supplies from a supplier, to point out a mistake by the letter's recipient, to reply directly to a request, to apologize for a wrong, or to convey goodwill. A business letter is sometimes useful because it produces a permanent written record, and may be taken more seriously by the recipient than other forms of communication.