> For the complete documentation index, see [llms.txt](https://adidas.gitbook.io/api-guidelines/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://adidas.gitbook.io/api-guidelines/asynchronous-api-guidelines/core-asynchronous-principles/messages/query.md).

# Queries

It is a special type of message which represents a request to look something up.

* They are always free of side effects (leaves the system unchanged)
* They always require a response (with the requested data)