Nested Segwit P2SH-P2WPKH

Working with P2SH now is a bit premature as we are dedicated this topic to part three of this guide. Nevertheless, the purpose of P2SH-P2WPKH transactions is to pay to a Segwit public key hash, inside a legacy P2SH. This type of transaction is less optimal than native Segwit but useful for backward compatibility.