All the upvotes you receive are acts of curation. Each upvoter is a curator, including the bots you purchase the votes from. When they upvote you, they also receive a share in the rewards, the curation reward.

You receive curation rewards when you upvote a post. You receive curation rewards calculated based on the upvote you cast, when you cast it, who else casts votes, and other metrics, which I don't pretend to fully understand.

Basically, you won't receive much in the way of curation rewards until you have a very, very large stake.

The curation rewards received from a given post are shared between all the upvoters of the post, between all the curators.

Hope that helps!