dPoW or delayed proof-of-work is a completely new cryptocurrency consensus mechanism, that is as secure as the proof-of-work blockchain to which it attaches itself to (In this case: Bitcoin), but does not require computing power and energy to be wasted. This is achieved by notarizing blocks created in the initial blockchain on the Bitcoin blockchain, ensuring that once the information is engraved on the Bitcoin blockchain, it would be required both blockchains in question to be compromised.
In simple words, the dPoW is a bolt-on layer that is simlar to a 2FA authentication. The mechanism stores the latest accepted Komodo block data onto a blockchain with stronger hashrate. This provides Komodo and its assetchains an anchor which all Notary Nodes and miners can rely upon if the network is attacked.
If the network happens to be attacked, the Notary Node network would swiftly notice the irregularity in the network and fall back on the latest known notarization. Hence, in order to compromise Komodo the assailant must compromise Komodo's standard PoW hashrate, the Bitcoin notarizations, and the notary node network.
This multi-level security is inherent to all assetchains deployed on Komodo Platform. That is why ChainZilla recommends such chains as minimum viable blockchains.
Examples of dPoW in action:
Game Credit is the first to integrate dPoW as a second layer of security: https://goo.gl/3bhwRt
Komodo defends network with dPoW: https://goo.gl/6yBFic