Casper and other Proof-of-Stake protocols enable token holders to earn rewards and take part in the protocol via staking. Staking allows you to stake your Casper tokens either by becoming a node operator or by staking CSPR coins with a validator on the network.
Node operators stake their tokens to earn the right to propose and approve blocks on the network. Additionally, they maintain servers connected to the Casper Network, allowing them to enable the Proof-of-Stake aspect of the network. On the other hand, you can participate in the protocol without maintaining a Casper node by delegating or allocating your CSPR tokens to a chosen node operator on the network. The node operator keeps a commission from the rewards generated from your staked tokens.
By participating in the protocol, you contribute to the network's decentralization and security while also earning rewards. Validators receive rewards proportional to their stake for taking part in the network, while delegators receive a share of the validator's rewards proportionate to their stake, minus the validator's commission (or delegation rate). The base annual reward rate is presently 9% of the total supply.