Hedera

Account Model (Critical Difference)

• Hedera accounts must be created before receiving funds — unlike Bitcoin/Ethereum, addresses don't exist until created
• Account creation costs HBAR — someone must fund the initial creation
• Account IDs are numeric (0.0.12345) — not cryptographic hashes like other chains
• Memo field available on accounts — can store small amounts of data
• Accounts can be deleted to recover balance — but requires all tokens and associations removed first

Account Creation

• New users need someone to create their account — can't just generate address and receive
• Exchanges create accounts on withdrawal — but self-custody requires creation first
• HashPack and other wallets offer account creation — may require payment or sponsor
• Testnet accounts free to create — use for development and testing

Transaction Fees

• Fees are extremely low and predictable — typically $0.0001 or less
• Fees paid in HBAR only — no gas token complexity
• Transaction fees set by network, not auction — no priority fee bidding
• Scheduled transactions cost extra — pay for scheduling plus execution

Token Service (HTS)

• Native token support without smart contracts — create tokens via Hedera Token Service
• Token association required before receiving — must explicitly associate with token ID
• Association costs small HBAR fee — limits spam tokens
• Fungible and NFT tokens supported natively — no need for custom contracts
• Token admin keys control supply, freeze, wipe — verify token permissions before trusting

Memo Field

• Transactions can include memo — used for exchange deposits like destination tags
• Memo is public and permanent — don't include sensitive data
• Some services require specific memo format — verify before sending
• Max memo size is 100 bytes — keep it short

Consensus and Finality

• Transactions finalize in 3-5 seconds — no waiting for confirmations
• Hashgraph consensus provides ordering guarantees — no MEV or frontrunning possible
• Fair ordering prevents manipulation — transactions processed in order received
• Mirror nodes provide historical data — main network doesn't store full history

Smart Contracts

• Hedera supports Solidity smart contracts — EVM compatible
• Contracts interact with native HTS tokens — best of both worlds
• Contract deployment costs more than simple transactions — plan accordingly
• State storage costs ongoing rent — unused contracts still cost

Staking

• Native staking to nodes — no minimum, no lockup
• Rewards paid automatically every 24 hours — no claiming needed
• Staking doesn't transfer funds — HBAR stays in your account
• Choosing a node affects decentralization — spread stakes across nodes

Keys and Security

• Accounts can have multiple keys — threshold signatures supported
• Key rotation possible without changing account ID — update keys if compromised
• Different key types: Ed25519, ECDSA (secp256k1) — affects wallet compatibility
• Admin keys on tokens can freeze/wipe holdings — check before acquiring tokens

Common Issues

• "INSUFFICIENT_PAYER_BALANCE" — need more HBAR for fees
• "INVALID_ACCOUNT_ID" — account doesn't exist, needs creation
• "TOKEN_NOT_ASSOCIATED" — must associate with token before receiving
• "INSUFFICIENT_TX_FEE" — rare, fee estimate was too low
• "ACCOUNT_FROZEN_FOR_TOKEN" — token admin has frozen transfers

Exchanges and Transfers

• Most major exchanges support HBAR — verify account ID format (0.0.xxxxx)
• Memo often required for exchange deposits — critical like XRP destination tags
• Account ID is not a wallet address — don't confuse with Ethereum-style addresses
• Verify recipient account exists before sending — non-existent accounts reject transfers

Network Services

• Hedera Consensus Service (HCS) — ordered message logging
• Hedera File Service (HFS) — store larger data on network
• Mirror nodes for queries — don't query mainnet for historical data
• SDKs available for major languages — JavaScript, Java, Go, Python