Ethereum was first mentioned in 2013 in a whitepaper by Vitalik Buterin, a developer who was working on Bitcoin at the time.
Buterin believed that Bitcoin should be made more customisable. He believed Bitcoin should go a step further than simply being a store of wealth and that it needed smart contract features to determine automatically when payments should occur, for example. This project was not taken up for Bitcoin, therefore Buterin created Ethereum in 2014 for this purpose.
Ethereum pioneered what’s known as an initial coin offering (or ICO), selling to initial investors about 60 million Ether tokens while the project was still in development. This kickstarted a large drive to develop and further promote the Ethereum ecosystem whilst paying for legal fees and development costs.
Since then, Ethereum has grown substantially. Multiple other projects have launched, and begun development on the Ethereum platform, with varying degrees of success.