# 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. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.harmony.one/home/general/technology/key-features.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.