> For the complete documentation index, see [llms.txt](https://docs.wundaflow.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.wundaflow.com/core-concepts/signals.md).

# Signals

There will likely be instances where you want to create a long-running workflow that waits for a specific action to occur from outside the blockchain.

This is where *signals* come into play.