The Ethereum Foundation was founded in 2014 by Vitalik Buterin, Joseph Lubin, and Gavin Wood to build the Ethereum Blockchain Project. The Ethereum Blockchain is created as a platform for Blockchain based applications and Smart Contracts. Ether is the currency that allows for transactions to occur and act as a small fee to miners for facilitating transactions.
Still in the early phases of being built, there have been two major applications operating on the Ethereum Blockchain: Initial Coin Offerings (ICOs, also known as Token Sale) and a game, called CryptoKitties.
ICOs are a mechanism for Blockchain based companies to raise funds and distribute their tokens. Ethereum is not the only Blockchain that ICOs can be completed on, but it has been the most popular due to the ease of creating new tokens using the ERC-20 standard structure.
CryptoKitties was the first Decentralized App (DApp link) to be operational on the Ethereum Blockchain. This DApp was a game that allowed you to buy digital assets in the form of digital cats. To learn more about this game, you can read our article: What Kittens Can Teach Us About Scaling Blockchains.