In a nutshell
For investors, Staking is a way of earning rewards for holding certain cryptocurrencies. Staking cryptocurrencies is a process that involves committing your crypto assets to support a blockchain network and confirm transactions.
Cryptocurrencies that allow staking use a “consensus mechanism” called Proof of Stake, which is the way they ensure that all transactions are verified and secured without a bank or payment processor in the middle.
For example, Tezos is a Blockchain designed as a proof of Stake, different from Proof Of Work models like Bitcoin which use substantial amounts of energy and specialised hardware to earn bitcoins (BTC).
7min to understand Tezos Blockchain