# GroupBy / concat rows

> For the complete documentation index, see [llms.txt](https://kotlin.github.io/dataframe/llms.txt).

* [groupBy](groupby.html) — groups rows of [DataFrame](dataframe.html) by given key columns.

* [concat](concat.html) — concatenates rows from several [DataFrame](dataframe.html) objects into single [DataFrame](dataframe.html).