Glossary
Staking
Locking a chain's native token to secure the network (in PoS) or to participate in a protocol's incentives, in exchange for rewards and slashing risk.
On a PoS chain, staking is how you become or back a validator: you (or a pool you delegate to) lock tokens, the protocol pays issuance to honest behavior, and slashes for provable misbehavior.
By extension, "staking" is used loosely for any protocol-level lockup that earns yield — though many of those products are really liquidity provision or governance incentives in disguise. Reading exactly what is being locked and what is being paid out tells you whether a "staking" yield is sustainable or emissions-funded.