The advantages of a public blockchain come with a trade-off. The fact that everything that happens on the public blockchain is added to a permanent record limits the scope of their use. You use a public ledger for things you want everyone to know. Imagine you want to make use of the public blockchain to prevent voter fraud in a general election. The public blockchain can give you a transparent election without fraud; the tradeoff of using a public blockchain is that you are forced to publish to everyone what they voted, thereby compromising the privacy of the voters.
Partisia Blockchain comes with an extra privacy layer. This allows for zero knowledge computations to happen in parallel with the activities on the public blockchain. If we go back to our example of a general election being run on a blockchain, the PBC is able to provide an election without the possibility of voter fraud and, at the same time, keep all the votes a secret. The combination of the technologies of blockchain and multiparty computation(MPC) expands the possibilities for blockchains immensely. For zero knowledge computation to happen simultaneously with the public activities on the blockchain, it is necessary to allocate part of the nodes of the network to focus on these tasks. To increase the security of these services even further, nodes that partake in them are selected through an economic staking model. This means that the owners of the computers handling the sensitive data have a common interest with the users of Partisia Blockchain to protect the data and preserve their privacy.