JSON-LD, period. Google has explicitly stated JSON-LD is preferred since 2017. Microdata and RDFa still parse correctly but add no benefit and complicate maintenance. Strip out any old Microdata when you migrate.
Three formats exist for adding structured data to a webpage:
**JSON-LD (JavaScript Object Notation for Linked Data):** A single `<script type="application/ld+json">` block in your `<head>` or `<body>`. Completely separate from your visible HTML. Easiest to author, easiest to validate, easiest to maintain.
**Microdata:** Schema attributes (`itemscope`, `itemtype`, `itemprop`) added inline to your existing HTML elements. Couples your structured data to your visual markup. Was the dominant format pre-2017.
**RDFa:** Similar inline approach to Microdata but using `vocab`, `typeof`, and `property` attributes. Most common in academic and library applications. Rarely used for SEO.
**Why JSON-LD wins for SEO in 2026:**
1. **Google's explicit preference.** Google has recommended JSON-LD as the preferred format since their 2017 search documentation update, reaffirmed annually since. 2. **Decoupled from visual markup.** Your designers can rebuild the page; your structured data doesn't break. 3. **Easier to validate.** Schema.org's validator and Google's Rich Results Test both handle JSON-LD cleanly with line-level error reporting. 4. **Easier to inject server-side or via tag manager.** You can add JSON-LD via Google Tag Manager without touching your CMS templates. 5. **No risk of breaking page rendering.** A malformed inline Microdata attribute can break visual layout in obscure edge cases. JSON-LD lives in a script tag — broken JSON just doesn't parse.
**The migration path if you have legacy Microdata:**
- Audit which pages have Microdata using Screaming Frog (Configuration → Custom → Search for `itemtype`) - Generate equivalent JSON-LD for each page type - Add JSON-LD blocks first; verify in Rich Results Test - Remove Microdata in a separate deployment - Re-validate; submit affected URLs to Search Console for re-indexing
**One Microdata exception:** if you're on a CMS that auto-injects Microdata (some WordPress themes, older Magento installs), don't fight it. The double-marked-up page (Microdata + JSON-LD) won't be penalized; Google merges signals from all formats present. Just make sure they don't contradict each other (e.g., different prices, different ratings).
**RDFa is essentially dead for SEO purposes.** If you encounter it on a legacy site, replace with JSON-LD on the next migration.
- **Is FAQ schema still worth implementing in 2026?** — Yes, but with reduced expectations. Google removed FAQ rich snippets from most non-authoritative sites in August 2023 and continued tightening through 2024–2025. FAQ schema still helps with semantic understanding and AI Overview citations, even when rich snippets don't display. - **Can I use Product schema for service businesses?** — Yes — Service schema (a Product subtype) is the right choice for service businesses. Don't use the generic Product schema for services; use Service, with proper offers, areaServed, and provider properties. - **How do I add AggregateRating schema without violating Google's guidelines?** — Only mark up reviews that are genuinely visible on the page, came from real customers, and are first-party (collected by you, not aggregated from elsewhere). Google's 2019 review snippet update made fake or third-party-aggregated review markup ineligible for rich results. - **Should I add Author schema for E-E-A-T?** — Yes — Author/Person schema with sameAs links to professional profiles is one of the few concrete technical things you can do to signal E-E-A-T. Pair it with a real bio page, byline on every article, and verified author identity across platforms.