A formal piece of writing is used when we do not have any idea of the person, or when we know the person but haven’t exchanged words, or we are not having familiar terms with the person who receives the letter. Here, we use formal language which indicates dignified and deferential regard for the reader. It is used when writing for academic, professional and legal purposes. Contractions : Informal: I donʼt believe that the results are accurate. Formal: The results are not believed to be accurate. Phrasal verbs : Informal: The balloon was blown up for the experiment. Formal: The balloon was inflated for the experiment. Slang/Idioms: Informal: It was raining cats and dogs. Formal: It was raining very heavily. No Abbreviations : Informal: DUET Dawood University of Engineering and Technology Formal: Use of Passive Voice: Informal The dinner is prepared by her.. Formal: She prepares dinner. Dear Sir/Madam, I am writing to inform you of my upset when I opened the lucky dip bag I had recently purchased with my own pocket money. I was disappointed to find that my favourite toy brand had been replaced with an inadequate copy, which even had pieces missing. I shall expect to be fully compensated for the distress and inconvenience this experience has caused me and hope that you send a replacement promptly. Yours sincerely, Miss F. James