> For the complete documentation index, see [llms.txt](https://tabbli.gitbook.io/tabbli/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tabbli.gitbook.io/tabbli/working-with-data/about-sub-collections.md).

# About sub-collections

Sub-collections are useful if you have a few related collections. For example, if we are talking about marketplaces there are could be collections like **Categories** and **Products** where **Products** is a sub-collection to **Categories**. In such case any record from **Products** collection could be related with any records from **Categories**.

![Parent collection records](https://1035471547-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Llw2w6GBgkdQD53tRYI%2F-LoK6u5QKF4tbOh4rOd5%2F-LoK8-pwY80aLkFaCtIS%2F%D0%97%D0%BD%D1%96%D0%BC%D0%BE%D0%BA%20%D0%B5%D0%BA%D1%80%D0%B0%D0%BD%D0%B0%20%20%D0%BE%2011.28.29.png?alt=media\&token=a8cef53b-dbd0-4ea5-b447-14d36f78b516)