> For the complete documentation index, see [llms.txt](https://docs.bancor.network/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.bancor.network/developer-guides/data-and-events/general-data/contextid.md).

# contextId

### What is contextId and how can it be used?

`contextId` is a unique value that is appended to data events in order to assist in grouping multiple data events together. This approach helps to reduce the data in every single event and at the same time provide a full data spectrum to anyone that is using the events to collect data.