The Sia is a blockchain that will allow you to store your data on a decentralized Cloud.
Concretely, instead of all your data being saved on the servers of an entity, they are registered in all the users who agree to allocate their storage spaces. It's a kind of hard disk in peer to peer.
With Sia, your data is cut, encrypted and distributed over the network, so no one can interfere. It saves your data separately on dozens of nodes, this guarantees a total availability of your data, even if users turn off their computers.
SIA uses a blockchain principle to store your files with other members of the network and this makes it always available. I assure you, no one will be able to consult your files (since it is encrypted) and even if several SIA clients are not available, your files will remain accessible.
This kind of project, although a bit complex at first glance, is probably the future of online storage. An inexpensive, secure, redundant storage and far from the hands of big boxes that use and analyze our data.