In a recent post on the Cardano forums the Proof of Stake mechanism is explained.
In short:
- Bitcoin transactions are validated by proof of work: computers doing calculations - requires a lot of energy)
- Cardano transactions are validated by proof of stake: being online and holding coins to secure transactions.
- Incentives motivate people to 'do the right thing': for example the rewards one gets for staking ADA coins and being online. For Cardano this requires a lot less computational power than with bitcoin which is a great + !
Read more about it on the Cardano Forums:
https://forum.cardano.org/t/summary-pos-delegation-incentives-lars-brunjes/11880