“EOS.IO” simply is a software that enables scaling of decentralized applications. The software architecture provides accounts, authentication, databases, asynchronous communication and secheduleing of “applications” across multiple CPU cores of clusters. https://www.eos.io/faq.html
If your outside the US see detailed instructions and make sure you register your eos public key so when the sale is over in June https://eos.io/instructions
The page is only available to IP in non restricted country