This chapter covers
- Understanding hard forks and soft forks
- Upgrading Bitcoin safely
- Understanding that users make the rules
To understand this chapter, you should be comfortable with concepts like the blockchain (chapter 6), proof of work (chapter 7), and the peer-to-peer network (chapter 8). If you had difficulties with those chapters, I suggest you revisit them before continuing with this chapter. Of course, you can also just try to read on anyway.
Bitcoin’s consensus rules can change in two ways: via either a soft fork or via a hard fork. These two types of changes are fundamentally different. In “Bitcoin forks,” you’ll learn about the differences between hard and soft forks and about what happens when different nodes run different consensus rules. You’ll need to understand this before learning how to safely upgrade Bitcoin’s consensus rules..
Rolling out a consensus rule change over the Bitcoin network can be difficult. Each Bitcoin node is sovereign, and no one dictates what software people should run—users decide for themselves. This makes it hard to roll out, or deploy, consensus rule changes without having broad user and miner support. The deployment mechanisms have evolved over time, and we’ll go through this evolution and explore the current state of deployment mechanisms.