Role of witnesses or block producers in Steem blockchain is to act as the network's governance body. Top 20 witnesses are producing blocks every minute while rest remain as backup witness and gets randomized chance every minute. Community elects them to represent their voice and each user can elect up to 30 witnesses. This role is integral part of consensus mechanism blockchain runs on and recommend user engagement to vote on trusted witnesses. Witnesses are compensated with SP for each block they create.