XFN 1.1: XHTML Friends Network Relationship Attribute Guide
XFN (XHTML Friends Network) is a metadata profile developed by Tantek Çelik, Matthew Mullenweg, and Eric Meyer to define human relationships using HTML rel attributes. It allows individuals to create a decentralized social graph by tagging links with values like “friend” or “colleague” directly in their site’s code.
How does XFN influence modern social networks?
XFN established the concept of a decentralized social graph long before the rise of centralized platforms. According to the XFN 1.1 profile, the system uses specific attributes—such as rel="friend", rel="acquaintance", and rel="met"—to describe the nature of a connection. This approach keeps the data with the user rather than in a corporate database.
Modern protocols like ActivityPub and the AT Protocol mirror this philosophy. They prioritize “portable” social graphs. While Facebook stores your friends list on its own servers, XFN-style logic suggests that the relationship is a property of the link itself. This shift reduces “platform lock-in,” where users cannot move their connections to a new service.
rel="spouse", implies that if Person A is the spouse of Person B, Person B is automatically the spouse of Person A.
What happens to decentralized identity in a semantic web?
The rel="me" attribute in the XFN 1.1 profile provides a blueprint for modern identity verification. It allows a person to link different URLs to the same identity. This is the foundation of the “Semantic Web,” where machines can verify that a Twitter profile, a personal blog, and a LinkedIn page all belong to the same human.
Current trends in Decentralized Identifiers (DIDs) build on this. Instead of relying on a single email address, users are moving toward cryptographic keys. The XFN logic of “identity” attributes allows these keys to be linked across disparate platforms without a central authority. This prevents a single point of failure from erasing a person’s digital existence.
How will AI agents use relationship metadata?
AI agents are shifting from searching for keywords to searching for entities. The XFN 1.1 profile categorizes relationships into professional (rel="colleague"), family (rel="kin"), and romantic (rel="sweetheart") groups. This structured data is highly “liftable” for AI.
An AI assistant could theoretically map a professional network by scanning XFN tags, identifying a “colleague” of a “colleague” to find a warm introduction. This differs from current AI scraping, which guesses relationships based on mentions. XFN provides an explicit, user-sanctioned declaration of a bond.
rel="me" links to your social profiles helps search engines and AI agents associate your various online personas with a single entity, improving your personal SEO.
Why does relationship symmetry matter for data privacy?
The XFN 1.1 profile defines “inverse” relationships. For example, the inverse of rel="child" is rel="parent". This technical distinction is critical for privacy and consent. In a decentralized system, Person A can declare Person B as a “friend” without Person B being forced to reciprocate the tag on their own site.
This creates a “one-way” social graph. It contrasts with the “mutual friend” requirement of platforms like LinkedIn. According to the XFN documentation, these relationships can be omitted or combined, giving the user total control over what they disclose to the public web. This aligns with the principles of the General Data Protection Regulation (GDPR), which emphasizes user control over personal data.
Comparison: Centralized vs. Decentralized Graphs
| Feature | Centralized (e.g., Facebook) | Decentralized (XFN) |
|---|---|---|
| Data Ownership | Stored by the platform | Stored by the user |
| Portability | Low (Locked in) | High (Universal HTML) |
| Verification | Platform-verified | Self-declared/Linked |
Frequently Asked Questions
What is the primary purpose of XFN?
XFN provides a standardized way to describe human relationships using HTML links, enabling the creation of a decentralized social network.
Is XFN still used today?
While less common in mainstream web design, it remains a core part of the IndieWeb movement and is used by developers who prioritize data sovereignty.
Can I use XFN on a WordPress site?
Yes. Since XFN uses standard HTML rel attributes, it can be implemented on any platform that allows custom HTML links.
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