EOS Blockchain is aiming to become a decentralized operating system which can support industrial-scale decentralized applications.
What has captured the public’s imagination are the following two claims:
1) They are planning to completely remove transaction fees.
2) They are claiming to have the ability to conduct millions of transactions per second.
Based on a white paper published in 2017, the EOS.IO platform is currently being developed by a private company, block.one, to be released as open-source software on June 1, 2018.  In order to ensure widespread distribution of the native token at the launch of the blockchain, one billion tokens are being distributed on the ethereum blockchain by block.one.  This will provide a distribution that anyone can use to launch the EOS blockchain once the software is released, while the CEO of block.one, Brendan Blumer, announced that block.one will support the EOS.IO blockchain with over one billion USD in funding from the token sale. On November 9, 2017, officialfuzzy mentioned the phrase "Exponential Operating System" as a reasoning being the name EOS.  On November 29, 2017, at BlockShow Asia Block.One revealed a publicly available testing environment called EOS.IO Single-Threaded Application Testnet (“EOS STAT”).  In the historically first rating of cryptocurrencies, EOS received the only B-rating besides Ethereum from the US rating agency Weiss (Bitcoin: C+) in January 2018. 
The aim of the platform is to provide decentralized application hosting, smart contract capability and decentralized storage enterprise solutions that solve the scalability issues of blockchains like Bitcoin and Ethereum, as well as eliminating all fees for users. EOS.IO accomplishes this by being both multi-threaded (able to run on multiple computer cores) as well using delegated proof-of-stake for its consensus protocol.  It aims to be the first decentralized operating system (EOS.IO) that provides a development environment for decentralized applications like Steemit, a social network with monetary incentives and BitShares, a decentralized cryptocurrency exchange (DEX).
The native token, EOS, is a utility token that provides both bandwidth and storage on the blockchain, in proportion to total stake (owning 1% of EOS tokens allows for usage of up to 1% of the total available bandwidth). EOS tokens also allow the owner to cast votes and participate in the on-chain governance of the blockchain, again in proportion to the owner's stake. The EOS platform will vote for 21 block producers during its launch, who will generate and validate blocks within a 500 ms block time.   General purpose and smart contract language to build upon the EOS platform will be WebAssembly (Rust, C, C++),  a portable stack machine that is developed at the World Wide Web Consortium (W3C) with engineers from Mozilla, Microsoft, Google and Apple. 
Block.one, EOS.IO Ecosystem and Everipedia
Block.one is a company registered in the Cayman Islands, which begun offering EOS tokens in June 2017 to the public, raising over $700 million.  Daniel Larimer is currently the Chief Technology Officer of block.one, notable for his role in building Bitshares, a decentralized exchange, building Steemit, a decentralized social media platform, developing delegated proof-of-stake and proposing the idea of a decentralized autonomous corporation.   
On December 6, 2017, Everipedia, a for-profit, wiki -based online encyclopedia, announced plans using EOS blockchain technology and work on a airdrop token called IQ to encourage generating information.  The IQ tokens are intended to be exchangeable for Bitcoin.  One of the goals of the company is to stop certain countries from blocking the content, by the integration of the blockchain model.  Once Everipedia is decentralized and hosted on the EOS platform, countries like Turkey and Iran that block Wikipedia will no longer be able to block it, via Everipedia's fork.  Mike Novogratz, CEO of Galaxy Investment LP, a cryptocurrency investment firm, and Block.one led a group of institutions that invested $30 million in Everipedia on February 8, 2018. Novogratz also funds EOS.IO Ecosystem, a $325-million joint venture between his Galaxy Digital LP and Block.one.