The network

Bittensor is a blockchain (the subtensor chain) that coordinates and pays for useful work. The work itself happens off-chain, inside subnets; the chain records who participates, measures agreement about who is doing good work, and emits the network's token, TAO, accordingly. The chain produces one block every 12 seconds.

Subtensor is a Substrate-based chain. Each block contains extrinsics — the submitted calls — and events; some events are emitted by the chain's own per-block hooks (emissions, epoch boundaries) rather than by any extrinsic.

Networks and endpoints

The SDK's network names resolve to public endpoints:

• finney — mainnet, wss://entrypoint-finney.opentensor.ai:443
• test — public testnet, wss://test.finney.opentensor.ai:443
• local — a dev node at ws://127.0.0.1:9944

Mainnet also has a public lite node at wss://lite.chain.opentensor.ai:443 and an archive node at wss://archive.chain.opentensor.ai:443. A lite node keeps only recent state; to query state older than roughly 300 blocks (block-pinned reads, historical snapshots) you need the archive endpoint or your own archive node. Any ws:// / wss:// endpoint can be passed to Client directly.

Subnets

A subnet is an independent incentive market, identified by an integer netuid. Each subnet has:

• an owner — the coldkey that registered it, who defines the incentive mechanism and sets its hyperparameters;
• miners — hotkeys registered on the subnet that produce whatever the subnet's mechanism demands (inference, storage, predictions, ...);
• validators — hotkeys with enough stake behind them to hold a validator permit; they score miners by setting weights;
• a liquidity pool pairing TAO with the subnet's own token, alpha.

Netuid 0 is the root network: it has no miners, no alpha token, and no validation work — it is the pool where TAO is staked directly. Root TAO stake counts toward validator stake weight on every subnet (see below) and earns a share of each subnet's dividends. Registration there is stake-based rather than burn-based; the root network's governance role is covered in the governance guide. By convention, root (TAO) is priced at 1.0 wherever subnet prices are summed.

Subnet slots are limited: a subnet holds at most max_allowed_uids neurons (default 256, and no lower than 64). Registering on a full subnet (burned-register) evicts the lowest-ranked non-immune neuron; a freshly registered neuron is protected for an immunity period, then competes like everyone else.

A neuron's stake weight on a subnet is alpha_stake + tao_stake × tao_weight — its alpha staked there, plus its root TAO stake scaled by the global TAO weight (currently 0.18 on mainnet, governance-set). Validator permits go to the top neurons by stake weight, up to the subnet's max_allowed_validators (default 128), recalculated every epoch.

TAO and alpha

TAO is the chain's native token (1 TAO = 10⁹ rao). Each subnet also has its own token, alpha, traded against TAO in the subnet's pool. Staking TAO into a subnet swaps it to that subnet's alpha at the pool price; unstaking swaps back. Alpha on one subnet is not worth alpha on another — the SDK's Balance type enforces this at the type level.

Spot prices come from the alpha-price read, and quote-stake / quote-unstake simulate a swap including fees and slippage before you commit.

Emissions and epochs

The chain continuously emits TAO to subnets, and within each subnet to its participants, in proportion to measured value. Each subnet runs on a cycle (its tempo): validators submit weights over miners during the epoch, and at the epoch boundary Yuma Consensus combines those weights — weighted by validator stake — into ranks, trust, and incentive, which set each participant's share of the emission. Delegated stake earns a share of its validator's dividends, minus the validator's take.

The numbers behind all of this — halving schedules, the emission-share formula, the 18/41/41 per-tempo split, and the consensus math — are on the Emissions page.

The epoch-status and blocks-until-next-epoch reads expose the timing; metagraph returns the full per-neuron state of a subnet in one call.

Who signs what

Every account is an ss58 address backed by a keypair. Operations divide by signer:

• coldkey — owns funds: transfers, staking, registration, subnet ownership.
• hotkey — operates on subnets: weights, serving an axon.

The wallets page covers how the two keys relate and how to manage them.