"The amount of formality in a piece of writing is defined by the register." It differs slightly from what we could term "tone" or "style." It might be viewed as a sliding scale, ranging from formal language (such as a legal document) to casual language (for example, a text message to a friend). The formal register is used in written documents that need to be correct, accurate, and not open to interpretation. This includes scientific papers, essays, reports, reviews, and letters. The informal register is used in written documents that do not have to be correct, accurate, or without ambiguity. For example, an article in a magazine would use the informal register because they do not want their readers to think that they are claiming accuracy for ideas expressed therein. The goal of using the formal register is to achieve clarity in communication. Use of the informal register may lead to confusion if not done properly, so it is important to identify which register is needed for any given piece of writing. As with many things in life, there is no single right way to use the registers. But understanding how they work will help you communicate more effectively when writing.