StemPower

Steem Power

This is known as a vested stored interest.

Steem Power is strictly for internal use in the Steem community. This determines the influence of a user on Steemit which is the value of a user upvote.

The higher your Steem Power the higher the value of your upvote.

Also note

Post rewards are influenced by the amount of STEEM Power held by the voter.