Social Consensus, Nakamoto Consensus

1. general

Agreement among the majority of nodes as to which block or blockchain to follow.

2. social consensus

Agreement among the community and developers over which direction the protocol should be developed, and how miners should choose to include transactions. This is often aligned with Miner/Nakamoto Consensus, but at times can differ, leading to interesting contentious forks.

3. nakamoto consensus

One of the core rules ideas which make Proof of Work (PoW) blockchains work and give them security. Nakamoto Consensus is a rule where miners follow the chain with the most accumulated Proof of Work (PoW) at any given moment, for a given ruleset.

This simple idea allows the blockchain to function in a decentralized, trustless way as miners are incentivized to cooperate and act honestly; building upon the same ledger as the rest of the network instead of splitting off.

Miners come across this situation commonly in two situations.

3.1 Double spend attempt

A miner tries to mine a double-spend transaction in a block against the rest of the network. Unless the miner is able to accumulate more proof of work than all the other miners combined, the honest chain will grow faster than the dishonest chain, forcing the miner to either waste resources mining their minority chain, or join the longest chain and act honestly.
Indirectly punishing the dishonest miner for violating Nakamoto Consensus as they don't keep the block reward for their now re-orged block.

3.2 Orphan blocks

Sometimes multiple miners discover a block so close to another they are both able to propagate their block to sections of the network.
Each other node will use the block they received first as the valid one and begin building upon that one, causing a temporary fork. Once a second block is found that chain becomes the longest chain and all the miners switch to building on that one.
In this case one miner loses their block reward, while acting completely honest.

* All terms and definitions may update as the Cryptionary improves.