> ## Documentation Index > Fetch the complete documentation index at: https://cts-docs.cosmos.network/llms.txt > Use this file to discover all available pages before exploring further. # Overview > What the digital ledger is and what it can run on. The digital ledger is the private blockchain that the Cosmos Tokenization Suite (CTS) runs alongside the bank's core. It holds tokenized deposits and gives the bank reach into custody services, other networks, and counterparty banks. The [Ethereum Virtual Machine](https://ethereum.org/en/developers/docs/evm/) provides the execution environment that runs Solidity smart contracts. CTS is EVM agnostic: all CTS and IBC contracts are written in Solidity, and CTS communicates with the chain through EVM JSON-RPC. ## What it can run on Cosmos EVM is the recommended path and ships in the evaluation environment. Hyperledger Besu is a supported alternative. A bank with its own Ethereum Virtual Machine chain can run the digital ledger on that chain instead. ## Why Cosmos EVM is recommended Any Ethereum Virtual Machine chain can host the digital ledger. Two features make Cosmos EVM the recommended chain. A precompile is a contract that executes common operations natively. Cosmos EVM ships these as precompiled contracts, which run significantly more efficiently than the same logic interpreted as Solidity on a generic chain. The second feature is IBC. Cosmos EVM integrates [Inter-Blockchain Communication](/ibc/overview) directly, so connectivity to counterparty banks and other networks is native to the chain. A bank's own chain requires a supported custom IBC deployment for the same connectivity, adding work that the bank takes on. See [Alternative Chains](/digital-ledger-support/alternative-chains). ## Properties of the chain The digital ledger is not a public blockchain. Several properties follow from its private design. The digital ledger is private and has a single operator: the bank operates it. Validators provide high availability and redundancy, not decentralized consensus security. Additional validators therefore add resilience, and production deployments should run more than one. The digital ledger exposes no public interface. CTS reaches it through EVM JSON-RPC from inside the deployment. Only the off-chain IBC relaying components are externally reachable, which limits the attack surface to components that require external access. Each bank runs its own chain, attesters, relayers, and tokens. See [Inter-Blockchain Communication](/ibc/overview). ## Related * [Architecture](/what-is-cts/architecture) explains where the digital ledger sits * [Components](/what-is-cts/components) describes what runs alongside it