It is appropriate to write using informal language in a postcard to a friend.
The most appropriate situation to write using informal language is when sending a postcard to a friend.
The appropriate situation to write using informal language is when you are writing a postcard to a friend. In this instance, it is acceptable to use a more casual, conversational tone and language because a postcard is typically a personal and informal way of communicating with someone you know well. When writing a postcard, you can use colloquial expressions, use contractions, and be less rigid in terms of grammar and syntax. However, it is important to note that in other situations, such as a job application (cover letter), legal document or scientific research article, it is more appropriate to use formal language to convey professionalism, clarity, and accuracy.
