The Steem White Paper was released in March of 2016 and updated in August 2017. It laid the foundation for what became the first social media blockchain.
This was the vision of Dan Larimer and Ned Scott, the co-founders of the network. The idea behind it was to incentivize community members to become content creators and curators. This would hopefully lead to the discovery of content the community found valuable.
Behind this was STEEM, a base layer coin that incentivized activity related to the ecosystem. This was done out of inflation, which was coded to decrease each year.
This was the second blockchain that Dan Larimer created. This followed up on the decentralized exchange he coded called Bitshares.