The greeting (Dear Sir or Madam) occurs before the subject in formal letters. Formal letters are prepared for both commercial and official objectives. They include business letters, correspondence to government agencies, and letters written to friends, family, and acquaintances. The word "greeting" is used because these letters are intended to be received by someone who will read them with respect to their sender. In informal letters, the greeting can appear at the end of the letter after all other content. It is not necessary to write a formal letter if you want to say something pleasant about someone else or give advice. Such letters are called "non-business" or "social" letters. In business letters, it is customary to begin each paragraph with an indented line followed by the topic sentence that carries out the idea contained in that paragraph. This ensures that the reader does not have to go back and reread the entire letter to understand its content. A simple example would be: "To start, I would like to tell you that..." Other ways of beginning paragraphs include using conjunctions or quotations. Conjunctions are words such as but (meaning "but") or so (meaning "so"), while quotations indicate that part of the sentence has been copied directly from another source.