Holochain is a data integrity protocol for distributed applications that uses a Distributed Hash Table (DHT) that in essence gives every participant their own "chain". But Holochain is not a blockchain, despite what the name implies. For example, publishing information on a DHT is similar to using BitTorrent.
Holochain intends to offer a distributed framework for generalized computing that supports programming and application development, something the Holochain team believes other crypto-projects do not offer.
On top of Holochain sits Holo, a distributed network of hosts and users sharing and consuming computing power to host decentralized applications (dapps), data repositories, etc., and hosts are paid for their services. But in the same way Holochain is not a blockchain, according to the development team, Holo is also not a token. It's an "asset-backed mutual-credit crypto-accounting system" that Holochain designed for use between participants and for immunity to volatile or speculative habits common to crypto-projects.
Holochain describes their protocol as an agent-centric distributed generalized computing system that consists of nodes who maintain individual sources of their respective interactions while simultaneously reinforcing the rules of the protocol network. This is the essence of Holochain's hash chain (not blockchain). But the team says Holochain has no definitive, network-wide "consensus" built into the protocol. Instead, peers simply "gossip" with each other about shared data, and if rules are broken, a given transaction is rejected by a validating peer.
Critical to Holochain's architecture is an understanding of agent-centric design. Cryptocurrencies are, according to the team, data-centric, which is to say they are built around the concept that data is a specific object. But Holochain aims to be agent-centric which supports the idea that a network and its protocol are not an actual objective thing. Instead, Holochain says it's a variety of shared, relative experiences.
Holo, on top of Holochain, aims to allow network participants to transform their computers into small sources of revenue by hosting compatible decentralized applications. Hosts set their own prices and select which dapps they want to host. Holo is an ERC-20 compliant token used to fuel peer-to-peer relationships on Holo.