YouTube ads gives the user flexibility to choose from the wide variety of ad formats available. The 5 main ones are Skippable in-stream. These are the videos that can be any length you want, appears within a video and skippable after 5 seconds.

Non-skippable in-stream. These videos appear within a video and a maximum of 15 seconds long. They are unskippable, so users have to sit through the entire duration.

Bumper. These are short videos, 6 seconds long and unskippable.

In-feed video. These videos appear on Youtube search results, home and watch next section. They do not appear in-stream. Users will click if interested to watch.

Outstream. These videos appear outside YouTube, known as video partners. They help you reach audiences outside of YouTube.