Layer 0 refers to the underlying infrastructure of blockchain, including the protocols, miners, and hardware that enable its operation. It is the foundation upon which the other layers of the blockchain are built and is responsible for maintaining the security and integrity of the network.

In the case of the XRPL, layer 0 includes the base protocol that is used to validate and process transactions, as well as the network of independent validating servers that maintain a copy of the ledger and facilitate transactions between users. The hardware used to support the operation of the XRPL, such as servers and other computing resources, is also part of layer 0.

Layer 0 is critical to the overall function and security of the XRPL, as it provides the foundation upon which the other layers are built and ensures the reliability and integrity of the network. It is important for the layer 0 infrastructure of the XRPL to be well-designed and implemented in order to support the smooth operation of the platform.