There have been 7 soft forks in the Bitcoin network (until May 2023):
Here’s a quick list:
- BIP 34: Enforced on November 28, 2010, this soft fork changed the block header version number from 0 to 1.
- BIP 66: Enforced on December 12, 2015, this soft fork changed the signature validation algorithm to be more secure.
- BIP 65: Enforced on December 12, 2015, this soft fork changed the way that block headers are hashed.
- BIP 91: Enforced on November 15, 2016, this soft fork delayed the BIP 141 difficulty adjustment algorithm.
- BIP 141: Enforced on November 15, 2016, this soft fork changed the difficulty adjustment algorithm to be more stable.
- BIP 143: Enforced on November 15, 2016, this soft fork changed the way that blocks are timestamped.
- Taproot: Enforced on November 15, 2021, this soft fork added support for Schnorr signatures, which improve privacy and efficiency.
Note: Soft forks are a way to upgrade the Bitcoin network without creating a split in the blockchain. They are typically used to add new features or fix security vulnerabilities.