Regardless of language you speak, you have grown up understanding the significance of using formal language in the situations that warrant that is best it. Those situations being those that either circle around a subject that is serious event, or involve individuals who we don’t know well.
Informal language, on the other hand, is much more commonly employed in the situations or scenarios where we are more stimulating and certainly will often involve individuals who we realize on a far more level that is personal.
The usage formal language is much more prevalent as soon as we write. Informal language sometimes appears more once we speak. That being said, there are occasions when writing can be less formal.