A piece of paper but speak your words.
We are living in the digital age and focusing on paperless environment. But, if you are running a business or organization and write a business letters, there will always be a need for letterhead. If you are a brand then you should send your business communications on your letterhead. It is create good business impression. If you are communicating on emails, it is possible that people may miss but if you send through letterhead there is no chance it will escape.