It’s our free token trading exchange for steem. You will have a lot to learn. When you use tags on posts it gets them in communities which are all similar to little steemits where they pay us in their community tokens too. It’s a side chain that runs on the steem blockchain.We all use it, it’s a very cool addition to using steemit!! Best to go to their site and learn about it.
https://steem-engine.com/