There are three tokens in the Steem system: Steem (provides liquidity - highly inflationary), Steem Dollar (pays interest - similar to debt; loose peg to US dollar based on 7 day moving average) and Steem Power (similar to equity in the platform). Steem power grows through a process akin to stock splits to protect holders from the inherent inflation of Steem. It's in the White Paper. The information is out there if you look...