# add

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

Returns [DataFrame](dataframe.html) with union of columns from several given [DataFrame](dataframe.html) objects.

API reference: [add](https://kotlin.github.io/dataframe/api-docs/core/org.jetbrains.kotlinx.dataframe.api/add.html)

```KOTLIN
df.addAll(df1, df2)
```

[Embedded content](resources/org.jetbrains.kotlinx.dataframe.samples.api.Modify.addDataFrames.html)

See [all use cases of 'add' operation](add.html).