Pay-to-Witness-Script-Hash (P2WSH) is the segwit variant of P2SH. The main advantage to using P2WSH over P2SH is that it can help lower transaction fees, and the primary reason to use a script hash instead of a public key hash is to accommodate multisig arrangements.

Like P2WPKH, a P2WSH address begins with a prefix of bc1q. However, it has a longer character length of exactly 62. Unlike the address types covered thus far, P2WSH addresses are created using the SHA-256 hashing function alone, without including RIPEMD-160, resulting in the increased character length. This was implemented cautiously, adding extra protection from a fairly nuanced and extremely unlikely multisig attack vector.

Pay-to-Script-Hash (P2SH) was introduced to bitcoin as a soft fork in accordance with BIP 16 on April 1, 2012. Like most forks, the story behind it is fascinating. P2SH shares a lot in common with P2PKH. The main difference is that the address is created by hashing a redeem script instead of hashing a single public key.

A redeem script can be thought of as coded instructions specifying how bitcoin received to the P2SH address can be spent in the future. There could be a wide range of possibilities, including multiple different public keys. The receiver, not the sender, determines the script details, and the spending instructions are not exposed publicly until bitcoin is spent out of the address.

While advanced users can construct complex scripts, the most common uses for P2SH have been to create nested segwit addresses (covered below) and multisig wallets. For example, a script can include three public keys and specify that signatures from any two of the corresponding private keys can spend the bitcoin. This would create a 2-of-3 multisig address.

P2SH addresses are exactly 34 characters in length, and they begin with a prefix of 3, as specified by BIP 13. Before the soft fork on April 1st, a handful of transactions experimented with this alternative prefix, the first of which is found in Block 170,052.