Let's answer the most common questions:
How does accidental forks happen❓
Different miners find a block at the same block height at the same time.
How does a blockchain correct for accidental forks❓
Over time, all the nodes will pick the longest chain and discard the shorter fork.
How is a hard fork update defined❓
An update that makes previously invalid blocks valid
How is a soft fork update defined❓
An update that makes previously valid blocks invalid
If an update reduce the block size limit from 1mB to 500kB, what type of update would that be❓
Soft fork update
If an update increase the block size limit from 1mB to 2mB, what type of update would that be❓
Hard fork update.
As Satoshi Nakamoto said:
Decentralized = better.
Decentralized = better.