How Transactions Work

Introduction

Transactions are the fundamental unit of execution in Stacks. Each transaction is originated from a Stacks account, and is retained in the Stacks network history for eternity. This guide helps you understand Stacks transactions.

Lifecycle

Transactions go through phases before being finally confirmed.

1

Generate

Transactions are assembled according to the encoding specification.

2

Validate and sign

Transactions are validated to confirm they are well-formed. Required signatures are filled in.

3

Broadcast

Transactions are sent to a node.

4

Register

A miner receives transactions, verifies, and adds them to the mempool, a holding area for all the pending transactions.

5

Process

Miners review the mempool and select transactions for the next block to be mined. Depending on the transaction type, different actions can happen during this step. For example, post-conditions could be verified for a token transfer, smart-contract defined tokens could be minted, or an attempt to call an existing smart contract method could be made.

6

Confirm

Miners successfully propose blocks with a set of transactions. The transactions inside are successfully propagated to the network when the stackers approve them.

A transaction can have one of three states once it is registered: pending, success, or failed.

Types

Stacks supports a set of different transaction types:

Type	Value	Description
Tenure change	TenureChange	A tenure change is an event in the existing Stacks blockchain when one miner assumes responsibility for creating new stacks blocks from another miner. A change in tenure occurs when a Stacks block is discovered from a cryptographic sortition. Carried out by stackers.
Tenure change block found	TenureChange-BlockFound	A TenureChange-BlockFound transaction is induced by a winning sortition. This causes the new miner to start producing blocks, and stops the current miner from producing more blocks.
Tenure change extend	TenureChange-Extend	A TenureChange-Extend, which is induced by Stackers, resets the current tenure's ongoing execution budget, thereby allowing the miner to continue producing blocks.
Token transfer	token_transfer	Asset transfer from a sender to a recipient
Contract deploy	smart_contract	Contract instantiation
Contract call	contract_call	Contract call for a public, non read-only function