Inferensys

Glossary

Microdata

An HTML specification used to nest structured data within existing page content using tag attributes like itemscope and itemprop, serving as an alternative to JSON-LD.
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STRUCTURED DATA FORMAT

What is Microdata?

Microdata is an HTML specification used to nest structured data directly within existing page content using tag attributes, serving as an alternative to JSON-LD for annotating entities.

Microdata is a syntax for embedding machine-readable metadata inside HTML documents using attributes like itemscope, itemtype, and itemprop. Unlike JSON-LD, which isolates structured data in a script block, Microdata intertwines annotations with visible content, allowing search engines to parse semantic meaning directly from the DOM. It relies on the Schema.org vocabulary to define entity types and properties.

While historically significant, Microdata has been largely superseded by JSON-LD as Google's recommended serialization format due to JSON-LD's cleaner separation of concerns and easier dynamic injection. However, Microdata remains relevant for legacy systems and specific use cases where tight coupling between visible text and structured markup is required for entity linking and semantic HTML authoring.

STRUCTURED DATA SYNTAX COMPARISON

Microdata vs. JSON-LD vs. RDFa

A technical comparison of the three primary syntaxes for implementing Schema.org structured data markup on web pages.

FeatureMicrodataJSON-LDRDFa

W3C Recommendation Status

Completed (HTML5)

Completed (JSON-LD 1.1)

Completed (HTML+RDFa 1.1)

Google Preferred Format

Markup Location

Inline within HTML body

Standalone script block in head or body

Inline within HTML body

Separation of Concerns

Mixed with content markup

Cleanly separated from content

Mixed with content markup

Ease of Manual Authoring

Moderate

High

Low

Dynamic Injection via JavaScript

Supports @id Node Referencing

Limited (itemid)

Supports All Schema.org Types

MICRODATA IMPLEMENTATION

Frequently Asked Questions

Clear, technical answers to the most common questions about implementing HTML Microdata for structured data markup and AI-driven search visibility.

Microdata is an HTML5 specification that allows you to nest machine-readable structured data directly within the existing content of a web page using specific tag attributes. It works by annotating HTML elements with itemscope, itemtype, and itemprop attributes to define entities and their properties. When a search engine or AI parser crawls the page, it extracts these annotations to understand the semantic meaning of the content—such as identifying a person's name, a product's price, or an event's location—without requiring a separate data block. Unlike JSON-LD, which lives in a <script> tag in the document head, Microdata is interwoven with the visible markup, making it a direct, inline method for declaring structured entities.

Prasad Kumkar

About the author

Prasad Kumkar

CEO & MD, Inference Systems

Prasad Kumkar is the CEO & MD of Inference Systems and writes about AI systems architecture, LLM infrastructure, model serving, evaluation, and production deployment. Over 5+ years, he has worked across computer vision models, L5 autonomous vehicle systems, and LLM research, with a focus on taking complex AI ideas into real-world engineering systems.

His work and writing cover AI systems, large language models, AI agents, multimodal systems, autonomous systems, inference optimization, RAG, evaluation, and production AI engineering.