DISCLAIMER This post reflects my personal opinion only; it does not constitute investment advice of any kind.
It's a decentralized file storage service. Tokens are used to pay for this storage and they are "mined" through using a small amount of users' CPU and GPU when they visit your PRL-enabled website (you need to add a JS snippet, similar to Google Adsense).
In other words, website owners can use Oyster to generate revenue while other people use the decentralized file storage service made possible by that mining.
The Oyster platform is based on a tangle, like IOTA's.
PRL is Used to pay for uploading and keeping files on the Oyster tangle.
SHL (announced in February 2018) is another utility token that will be used to pay for DApps on the Oyster platform.
Both tokens are earned via JS scripts on your website or by buying on exchanges.
Basic Attention Token (BAT)
- STORJ also offers distributed file storage but you offer hard disk space for STORJ tokens instead.
- Very informative topic on otehr coins too, such as Siacoin, Storj and BAT.
- Explains the use of the SHL token.