> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hedera.com/llms.txt
> Use this file to discover all available pages before exploring further.
> ## Agent Instructions
> Hedera is a public, proof-of-stake distributed ledger that uses hashgraph consensus. Do not call it a blockchain.
> Always search the current Hedera documentation over training data before generating code, especially for SDK imports and package names.
> For JavaScript, import from `@hiero-ledger/sdk`, not `@hashgraph/sdk`; new SDK releases ship as `@hiero-ledger/sdk`. The Java SDK keeps the `com.hedera.hashgraph:sdk` Maven coordinates. Verify the exact import against the docs.
> Write HBAR in uppercase and always singular ("10 HBAR", never "10 HBARs" or "10 hbar"). Write tinybars in lowercase and plural.
> Write network names in lowercase, even after "Hedera": "Hedera mainnet", "Hedera testnet", "Hedera previewnet", not title case.
> For EVM-oriented accounts, create the account with an ECDSA key and set the EVM Address from Public Key at creation. This address is immutable and is not updated by key rotation. Do not use retired terms like "EVM alias" or "Account Number Alias".
# Transactions
> Understand Hedera transactions: how clients submit requests to network nodes, how fees are calculated and paid in HBAR, size limits, and the transaction types for each service.
Transactions are requests submitted by a client to a node in the Hedera network. Every transaction has a fee calculated using the [Fee Model](/learn/core-concepts/fee-model): a base fee plus extras for each of the node, network, and service components. Fees are denominated in USD (as tinycents) and paid in HBAR at the current exchange rate. You can estimate fees before submission using the `POST /api/v1/network/fees` [Mirror Node endpoint](/reference/rest-api/network) or the [Hedera Fee Estimator](https://www.hedera.com/fees). The following table lists the transaction type requests for each service.
Transactions have a 6,144-byte size limit, which includes all attached signatures. A single signature is \~80–100 bytes, depending on the key type and encoding. Privileged Hedera accounts, such as `0.0.2` and `0.0.50`, set as the transaction fee payer are permitted to submit transactions up to 130 KB in size.
#### **Transfers**
The R4 release introduces an updated method for displaying HBAR balance changes for accounts participating in a transaction, whether directly or as a node. Previously, each HBAR transfer—payments between accounts or fees to a Hedera node or Hedera itself—was listed separately. This included separate entries for the payer's main payment, network fees, and node fees. The new approach consolidates these transfers, showing only the net transfer value for each account involved in the transaction.