* Letters have existed for thousands of years. The earliest known examples are from ancient Mesopotamia, dating back to 3000 BCE.
* Different cultures and time periods have their own letter writing traditions. The ancient Egyptians, Greeks, Romans, and many other civilizations developed their own forms of letter writing.
* Letter writing continues today. While technology has changed how we communicate, people still write letters for personal, professional, and official purposes.
To get a more specific answer, you need to clarify your question:
* What specific culture or time period are you interested in?
* Are you asking about the invention of writing itself, or the development of letter writing as a form of communication?
* Are you interested in a particular type of letter, like love letters or business letters?
Once you provide more context, I can give you a more relevant answer!