Microformats

Microformats are a set of simple, open data formats that use standard HTML class attributes to embed machine-readable structured data within human-readable web pages. As one of the earliest approaches to in-page structured markup, Microformats pioneered the idea that web pages could simultaneously serve human readers and automated data consumers without requiring separate metadata files or complex additional syntax. Predating both RDFa and Microdata, Microformats influenced the direction of structured data on the web and remain actively used, particularly within the IndieWeb movement.

Background

The Microformats community emerged in 2004, driven by web developers who wanted a pragmatic, low-barrier approach to structured data. Key figures including Tantek Celik, Kevin Marks, and others were frustrated by the perceived complexity of earlier Semantic Web technologies like RDF and XML. They observed that web authors were already using informal HTML conventions -- such as consistent class names for contact information or event details -- and proposed formalizing these patterns into reusable specifications.

The first generation of Microformats included hCard (based on the vCard standard) for contact information, hCalendar (based on iCalendar) for events, hReview for reviews, and XFN (XHTML Friends Network) for social relationships. These formats gained significant traction, with search engines beginning to parse and display them in search results.

The second generation, Microformats2, was developed starting around 2010 to address parsing complexity and consistency issues in the original specifications. Microformats2 introduced a uniform prefix-based naming convention (h-card, h-entry, h-event, h-feed) and a standardized parsing algorithm that made implementation significantly more straightforward.

Purpose & Scope

Microformats work by assigning specific CSS class names to HTML elements. A parser encountering these class names can extract structured data from the surrounding markup. This approach requires no changes to HTML syntax, no additional attributes, and no RDF knowledge -- just the disciplined use of class names that already exist in the HTML specification.

The design philosophy prioritizes simplicity and human readability. Microformats specifications are developed based on real-world publishing patterns rather than abstract data models. New formats are only standardized after documenting existing usage across multiple independent websites.

Key Microformats2 Vocabularies

Governance & Maintenance

Microformats are developed through an open community process centered on the Microformats wiki at microformats.org. The community follows a research-driven specification methodology: proposed formats must demonstrate existing publishing patterns, multiple independent implementations, and real-world usage before being accepted. There is no formal standards body; governance is community-based with rough consensus among active participants. Tantek Celik has served as a long-term steward of the project.

Notable Implementations

The IndieWeb community is the most active contemporary user of Microformats, building decentralized social web tools that use h-card, h-entry, and h-feed for identity, content publishing, and social interactions. Webmention, a W3C Recommendation for cross-site notifications, relies heavily on Microformats2 parsing. Major search engines historically supported Microformats for rich snippets, though JSON-LD with Schema.org has become the preferred format for search engine optimization.

Related Standards

• RDFa -- A W3C Recommendation for embedding RDF in HTML, using a different attribute-based approach
• Schema.org -- The dominant vocabulary for web search structured data, expressible in multiple syntaxes

Further Reading

• Microformats Wiki -- Specifications
• Microformats2 Specification
• Getting Started with Microformats