There are many types of formal letters. In this article, we detail when to use a formal letter format, the different types of formal letters and how to write your own.Learn how to write a formal letter with proper format. Check out various writing tips on formal letter writing with samples, types, and more. There are two basic styles of letters: block form and indented form. The samples below will help you determine which style you prefer. A formal letter follows a specific format and uses formal English language. Keep reading to find out how to write formal letters. Put your address in the top-right corner. The main types of formal letters discussed are letter of enquiry, order letter, application letter, complaint letter, and adjustment letter.