Apology<\/strong> letters are letters that fall both into the formal as well as informal letters. If written in a formal context, an apology letter will be shirt and practical and concise, ending after the apology has been made. However, if the apology letter is informal, as most apology letters are, then the letter can be really big or small depending on the people involved in it. Apology letters are written frequently between parents and children and even more frequently between friends and lovers and spouses.