we literally assemble the blockchain with servers we operate. Witnesses vote on settings that dictate a variety of functions around here like size per block or the price of the currencies for post reward calcs etc. People also have a variety of projects they work on. Some are like good karma who created esteem. Some are like gtg that manages a lot of infrastructure. Tim Cliff helps in steemit chat for help all the time. Riverhead built steemit chat. I run a group for ~4000 minnows to work together and grow together. If you like their work and their projects than toss them an upvote.