I was reading an article about the different types of Bitcoin addresses recently and I came across the topic of a wrongly sent transaction. As an option to ask the (otherwise unknown) recipient of the transaction to return the sent bitcoin, the article mentioned the possibility of making another (extra small) transaction with the insertion of a text message using the OP_RETURN function. Good thing is that this text can be viewed by finding the transaction in any block explorer, but on the other hand any outputs with OP_RETURN are provably unspendable, so OP_RETURN outputs can be used to burn bitcoins as well. I have to admit that I had no idea about this.
