Twitter's equivalent of Open Graph — meta tags that control how a URL renders in tweets and previews. Falls back to OG tags when missing.
Twitter Cards in plain English
Twitter Cards are <meta> tags with twitter:* prefixes that tell Twitter (and X) how to render link previews when your URL is tweeted. The core tags: twitter:card (the card type — summary, summary_large_image, app, player), twitter:title, twitter:description, twitter:image. Without explicit Twitter Cards, Twitter falls back to your Open Graph tags, which works adequately but means you can't differentiate Twitter-specific behavior.
The most-used card types: summary (small square thumbnail next to title and description, used for most content), summary_large_image (large rectangular image above title and description, used for visual content like blog posts and product showcases), and player (for embedded video/audio — most ecommerce won't use this). For ecommerce product pages, summary_large_image with a 1200x630 product photo is the standard.
Twitter has historically validated Cards via the Twitter Card Validator tool, but the tool was removed in 2023 as part of broader Twitter→X changes. Currently, the only way to test is to actually tweet a URL from a test account and see how it renders. Cards still work, but the validation flow is awkward.
Common gotchas: twitter:image needs to be an HTTPS URL (HTTP-only images are blocked from rendering), Twitter caches previews for at least a week (changes to your tags don't reflect immediately), some accounts with no profile image or no Twitter handle in the twitter:site tag get reduced preview functionality, and very small images (under 200px) render as a tiny thumbnail or get suppressed entirely.
Why twitter cards matters for ecommerce
For ecommerce stores doing organic social on Twitter/X, Twitter Cards directly affect whether shared product links get clicked. A summary_large_image card with a hero product shot and clear title gets clicks; a basic summary card with no image gets ignored. Even if Twitter isn't a primary channel, your customers, suppliers, and press contacts will share your URLs — those previews are how your brand looks in those conversations. Set Twitter Cards once at the template level; benefit forever.