In Hive's Delegated Proof of Stake (DPOS) blockchain, the “witnesses” are elected. They are the ones who generate new blocks…they run the chain. Witness nodes are special in that they validate blocks. Other chains (like Bitcoin) call them “miners” and others might use another term, such as “validators.” The top 20 are the main witnesses. They alternate producing blocks, and since Hive's block time is about 3 seconds, they produce roughly one block per minute. Witnesses outside of the top 20 also produce blocks, though less often.
To vote for witnesses
All Hive users can vote for witnesses using various Front ends. Up to 30 witnesses can be selected at any one time. The weight of the Hive user's vote depends on that user's Hive Power (HP). The greater the HP, the greater the vote's weight.