On the Hive blockchain, witnesses serve the role of validating signatures and timestamping transactions by including them in blocks. A block is any group of transactions (posts, votes, transfers, etc) that update the state of the database.

Witnesses are generally expected to manage a reliable block-producing node, implement a failover system, maintain a public seed node, tune blockchain operating parameters, publish correct price feeds, author/discuss improvement proposals, review code changes, and be active! Some contribute to core repositories. Some fund the development of other apps and infrastructure projects.

By voting for a witness, YOU choose which ones you trust to ensure the security of the blockchain, and therefore the security of your assets.