If you’ve watched a YouTube video you’ll be intimately familiar with annotations on videos which invite you to check out other videos the creator has made, link to other sites or just remind you to like the video. Google has looked into a way to make annotations like this work better across their platforms and has decided their card interface is the best and will begin using it on videos.
The cards, which are available to YouTube creators in the Video Editor will be divided into six types of cards, of which the YouTube blog gave five: Merchandise, Fundraising, Video, Playlist, Associated Website and Fan Funding.
Google says that because the cards work across mobile and desktop, you will have more flexibility to share what you want. Google is looking for feedback on the cards to help bring as much functionality as the current annotations do before rolling out the update widely. YouTube has already rolled the feature out to some videos though and you can check examples on the YouTube Creators blog, but if you need more information you should check the Google Help Centre.