> For the complete documentation index, see [llms.txt](https://dev.teaproject.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dev.teaproject.org/z_glossary/txn.md).

# Transactions

Transactions (txns) are also called [commands](/z_glossary/commands.md) or events.

A txn is generated by a [back\_end\_actor](/z_glossary/back_end_actor.md) or [blockchain\_listener](/z_glossary/blockchain_listener.md) and executed in a [state\_machine\_actor](/z_glossary/state_machine_actor.md) to update the [state](/z_glossary/state.md).

A txn is the only outside trigger that's able to change the [state](/z_glossary/state.md). In other words, all state changes are triggered by txn(s).

## Some examples of txns

Alice sends 10T to Bob. This is a transfer txn. Every 1000 blocks, we run a clean up of the blockchain storage. This is a [blockchain\_listener](/z_glossary/blockchain_listener.md) triggered txn. It looks like a cron job. If the blockchain notices a new TApp is created, then it performs a **generate tapp account** task. Although this is also a [blockchain\_listener](/z_glossary/blockchain_listener.md) triggered txn, it's not considered to be like a cron job.

## Binary successful or failed on execution

A txn can be successfully executed or failed. If it's successful, it may or may not change the state. But if it's failed, it will definitely **NOT** change the state.

There are **no partially successful txns**. They're either fully successful or totally failed.