What is the difference between a formal and informal writing style?

Formal writing is characterized by its adherence to conventional grammatical standards and a clear avoidance of colloquial language. This style is typically utilized in academic, professional, or official communications where clarity, precision, and a respectful tone are essential. By using complete sentences, complex structures, and a wider vocabulary, formal writing conveys ideas in a serious manner suitable for its context.

The correct answer reflects this distinction by highlighting that formal writing avoids colloquialisms — expressions that are more casual and conversational. By sticking to grammatical conventions, formal writing enhances its credibility and ensures that the message is conveyed in a straightforward and universally understood manner. This is particularly important in contexts where the writer needs to convey respect or authority, or where the audience may not share the same background or familiarity with informal language.

In contrast, the other options present incorrect or misleading attributes regarding formal and informal writing. For example, the inclusion of slang and colloquialisms is a hallmark of informal writing, while the notion that informal writing is always longer in form does not hold true, as the length of writing can vary regardless of the style. Both of these points help underscore the importance of recognizing the nuances between writing styles based on the audience and purpose of the communication.