There are 2 kinds of votes.

• up and downvote of posts
• witness votes.
  Minibot, nanobot and microbot do the first kind.
  They are upvote bots. Upvotes for money. Like buildawhale

Witness voting is something different.
The steem blockchain is forged by dpos, a special version of PoS, proof of stake.
User can vote for upto 30 witnesses. The 20 with the most votes make each one block every minute(a block every 3 seconds) , the other, below top 20 witnesses, are chosen randomly weighted with their votes as backup.
Everything else, providing community support, helping minnows, developing software, contributing to the steem git, etc. Is just on top of that and gives them of course more votes from other users.
I am currently on mobile, sorry, no link here on the fly. But look for @timcliff he did write a bit about the whole shabang:)