> For the complete documentation index, see [llms.txt](https://docs.yarchain.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.yarchain.org/whitepaper/project-mechanics/witness-operations.md).

# Witness operations

When a node sees a transaction on a connected network, it writes it to what's called a "witness transaction". A witness is a message from a node that says, "I saw that". So it could be:

* "I saw someone send 1 BTC to YAR ";
* "I saw someone change the status of data on YAR ";
* Or, "I saw someone change the status of a smart contract on YAR ".

All nodes send witness transactions to the system all the time. Witness transactions have a standard structure, regardless of which network they originate from. A Bitcoin transaction is different from a BNB SmartChain transaction, but in YAR they look the same.