It uses Ethereum for the logic, and IPFS for the storage back-end. That might sound a bit hand-wavy, but I'd honestly just recommend downloading it (after you

It uses Ethereum for the logic, and IPFS for the storage back-end. That might sound a bit hand-wavy, but I'd honestly just recommend downloading it (after you get into the beta) and seeing for yourself - its very easy to use, you don't have to setup or deal with either Ethereum or IPFS, and the GUI is intuitive enough that you shouldn't have any problem just launching it and using it. The initial startup time is a bit of a usability issue - it takes some minutes to get itself established on the network - but once up and running its kind of refreshing to be able to do all the things, without any of the typical social-media grot to deal with.