Blockchain//Transaction

- Lifecycle: wallet signs → RPC node receives → mempool → gossip to peers → validator includes in block → confirmed.

Lifecycle: wallet signs → RPC node receives → mempool → gossip to peers → validator includes in block → confirmed.

eth_sendRawTransaction: accepts a pre-signed transaction. The RPC node just relays it.

eth_sendTransaction: requires the node to have the signing key. Legacy, rarely used now.

Valid signature alone isn't enough: sender must have ETH to cover gas × gasPrice (upfront cost)

Nonce: sequential counter per account, prevents replay and enforces transaction ordering.