A blockchain is a database no one owns, so someone has to decide what the next page says. Consensus is that decision procedure: proof of work makes miners burn compute for the right to write it, proof of stake makes validators post collateral they lose if they cheat. Different economics, same goal — making lying more expensive than honesty.
The properties cascade from the choice: PoW buys battle-tested security with energy; PoS buys efficiency and fast finality with different trust assumptions. For a builder the takeaway is simpler — your app's security inherits the chain's, so the consensus under it is part of the architecture you chose.
Related terms
On-chain
Recorded on the blockchain itself — permanent, public, verifiable by anyone — as opposed to off-chain data in someone's database.
Solana
A high-throughput, low-fee blockchain — thousands of transactions a second at fractions of a cent — built for applications that need speed.
Smart contract
A program deployed to a blockchain that runs exactly as written, that anyone can call, and that usually cannot be changed afterwards.
