The 'Add to Playlist' function allows users to include a video or song in an existing or newly created playlist. This feature is typically found in video streaming platforms, music apps, or media players.

To add a video or song to a playlist, users usually need to follow these steps:

1. Find the desired video or song and navigate to its information page.
2. Click on the 'Add to Playlist' icon/button.
3. Select the target playlist or create a new one.
4. Confirm the addition by saving or finalizing the changes.

By utilizing the 'Add to Playlist' option, users can easily organize and access their favorite or preferred content at any time.