X cards are useful if you want a “card” added to any post that contains a link to your content. For example, if you or a supporter shares a link to an Engaging Networks petition then a X Card can automatically add a linkable image, title and description to the posted tweet.
A card looks something like this:
Anyone posting the link to that page will have it “converted” into the card in the panel below the post text.
Since our October 2020 update, you can manage your X cards within the social settings of the page. See this article for more.
As usual, you should fully test every stage of your campaign before launching it to ensure the content produced is as expected. You can read more on X cards here.