# Key Features ## Secure, Random State Sharding Harmony has transcended the blockchain trilemma by bringing the best research to production. Sharding is proven to *scale* blockchains without compromising *security* and *decentralization*. We divide not only our network nodes but also the *blockchain states* into shards, scaling linearly in all three aspects of machines, transactions and storages. To prevent single shard attacks, we must have a sufficiently large number of nodes per shard and cryptographic randomness to re-shard regularly. Each shard has 1/4 of nodes for strong security guarantee against Byzantine behaviors. We use Verifiable Random Function (VRF) for un-biased and unpredictable shard membership. ## Fast Consensus w/ Instant Finality Harmony has innovated on the battle-tested Practical Byzantine Fault Tolerance (PBFT) for fast consensus of block transactions. Our Fast BFT (FBFT) leads to low transaction fees and 1-block-time finality in Harmony Mainnet. We use Boneh–Lynn–Shacham (BLS) constant-sized signatures to commit blocks in a single round of consensus messages. We achieve 2-second block time with *view changes in production* against adversarial or unavailable leaders. Harmony Mainnet was launched in June 2019. Our network has produced 30M+ blocks with 450k+ transactions in *publicly traded, native* ONE tokens. ## Effective PoS & Token Economics Harmony has designed a novel Proof-of-Stake (PoS) mechanism for network security and economics. Our Effective Proof-of-Stake (EPoS) reduces centralization and *distributes rewards fairly* to thousands of validators. Our staking mechanism supports delegation and reward compounding. To support 100% uptime but fully open participation, EPoS slashes validators who double-sign and it penalizes elected but unavailable nodes. Harmony Economics Model caps the annual issuance at 441 million tokens (about 3% rate in long term). Our model gives validators a simple and predictable return. All transaction fees are burnt to offset the issuance, naturally leading to *zero inflation* when our network usage becomes high. ## On-chain Verifiable Randomness Harmony allows smart contracts to receive random numbers on chain, using a Verifiable Random Function (VRF) powered by distributed randomness generation (DRG). This allows any DAPP in the Harmony ecosystem to leverage randomness without relying on off-chain oracles.