A protocol called Skynet was created on the Sia blockchain to offer decentralized storage, facilitating file sharing and content distribution across the internet. It can be viewed as an alternative internet infrastructure in many ways.
The purpose of Sia is to enable users to lend out a portion of their hard drives. Other users have full control over their data because they can rent a portion of the hard drive to store encrypted data. The borrower uses Siacoins (SC), the native token of Sia, to pay for that space.