[//]: # (title: Multiple DataFrames)
<show-structure depth="3"/>

* [`add`](add.md) — union of columns from several [`DataFrame`](DataFrame.md) objects
* [`concat`](concat.md) — union of rows from several [`DataFrame`](DataFrame.md) objects
* [`join`](join.md) — sql-like join of two [`DataFrame`](DataFrame.md) objects by key columns
* [`joinWith`](joinWith.md) — join of two [`DataFrame`](DataFrame.md) objects by an expression that evaluates joined [DataRows](DataRow.md) to Boolean