---
slug: what-is-link-protocol-history
title: What Is the History of Link Protocols
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---

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# What Is the History of Link Protocols

## §SELF — what-is-link-protocol-history

**What this page is:** A chronological account of the systems and protocols that use links as their primary organizing mechanism, from 1945 to the present.
**What it explains:** How the concept of a "link" evolved from a human's saved trail of document references into machine-readable, content-addressed, capability-carrying protocol elements.
**Why read it:** To understand that the history of links is the history of making connections between pieces of information more expressive, more verifiable, and more actionable — and why the most recent chapter requires a new kind of reader.

### What Link Protocol History Is

Link protocol history is the sequence of inventions, starting in 1945, in which links (connections between discrete pieces of information) became the central mechanism for organizing, navigating, and reasoning about data. Each step made links more expressive, more machine-readable, or both.

### Why It Matters

Every time the nature of a link changed, the way people and machines could use information changed. A link that only a human can follow enables browsing. A link that a machine can interpret enables automation. A link that carries meaning about what action it permits enables autonomous decision-making. Understanding this progression clarifies what the next generation of protocols must provide.

### The Key Idea

The key idea is that links started as references for humans to follow and evolved into structured, machine-interpretable protocol elements that carry semantics, provenance, and capability. The throughline across 80 years is increasing expressiveness and increasing machine readability. The missing ingredient until recently was a general-purpose machine reader that could interpret links and decide what to do with them.

### Timeline and Contributions

**1945 — Vannevar Bush: The Memex.** Bush proposed a device in which documents are connected by "trails" — sequences of links that a user creates and saves. The links are human-created and human-followed. The Memex was never built, but it established the concept of associative linking as an alternative to hierarchical filing.

**1963 — Ted Nelson: Hypertext and Xanadu.** Nelson coined the term "hypertext" and began building Xanadu, a system with three properties that Bush did not propose: bidirectional links (each link knows its reverse), transclusion (including part of one document inside another by reference, not by copy), and versioning (every version of a document remains accessible). Nelson's links carry more structure than Bush's trails, but Xanadu was never completed as a working system at scale.

**1968 — Doug Engelbart: NLS (oN-Line System).** Engelbart demonstrated the first working hypertext system. NLS had structured links between documents, collaborative editing, and a pointing device (the mouse). The links were machine-stored but still primarily for human navigation. This was the first proof that linked document systems could be built and used.

**1989 — Tim Berners-Lee: HTTP, HTML, URL.** At CERN, Berners-Lee built the World Wide Web. Three components: HTTP (the protocol for requesting documents), HTML (the format for documents containing links), and URL (the addressing scheme for locating documents). The Web's links are one-way (no knowledge of reverse connections), location-based (the URL points to a server and path), and universally addressable (any document can link to any other). The Web scaled because it was simple, but the simplicity meant links could break (the server disappears) and carried no semantic meaning.

**2000 — Roy Fielding: REST and HATEOAS.** Fielding, in his doctoral dissertation, named REST (Representational State Transfer) and HATEOAS (Hypermedia as the Engine of Application State). The key idea: a server response contains not just data but also links describing what actions the client can take next. The link carries capability information. This was the first systematic attempt to make links in protocol responses machine-actionable rather than merely human-navigable.

**2001–2010 — W3C Semantic Web: RDF and Linked Data.** The Semantic Web initiative introduced RDF (Resource Description Framework), a graph data model in which every node and every edge is a URI (a globally unique identifier). Links in RDF are typed: the edge between two nodes has a label that describes the relationship. This makes links machine-readable in a specific sense — a machine can traverse the graph and know what each connection means.

**2006 — Tim Berners-Lee: Linked Data Principles.** Berners-Lee published four rules: (1) use URIs as names for things, (2) use HTTP URIs so people can look them up, (3) provide useful information when someone looks up a URI, and (4) include links to other URIs. These rules turned the Semantic Web from a technical specification into a set of practices for publishing connected data.

**2014 — Juan Benet: IPFS.** IPFS replaces location-based links with content-addressed links. The link target is not a server address but a cryptographic hash of the content itself. This removes link rot (the content is retrievable from any node that has it) and guarantees integrity (the hash proves the content is exactly what was linked). Links become verifiable.

**2020+ — Large Language Models (LLMs).** LLMs are the first general-purpose systems that can read links, understand the text at both ends of the link, and decide whether to follow the link and what to do with what they find. Previous link consumers were either human (browsers) or narrowly specialized (crawlers with hardcoded behavior). LLMs can interpret links in context.

### What Each Step Got Right

- **Bush:** Established that associative trails (non-hierarchical connections) are a natural way to organize knowledge.
- **Nelson:** Recognized that links should be bidirectional, that inclusion by reference (transclusion) is preferable to copying, and that versions should persist.
- **Engelbart:** Proved that a linked document system could be built, used collaboratively, and augment human intellect.
- **Berners-Lee (Web):** Showed that radical simplicity and open participation enable global scale. Location-based addressing was the right trade-off for bootstrapping.
- **Fielding:** Demonstrated that links in protocol responses can carry application state and guide client behavior.
- **Semantic Web:** Created a graph model where link types are explicit and machine-traversable.
- **Berners-Lee (Linked Data):** Provided practical rules for publishing connected, machine-readable data.
- **Benet:** Showed that content-addressing removes the fragility of location-based links.
- **LLMs:** Provided the first readers capable of interpreting links in full semantic context.

### What Was Left Unfinished or Failed

- **Xanadu never shipped at scale.** Nelson's vision of bidirectional links, transclusion, and versioning remains unrealized in mainstream systems. The Web adopted simpler one-way links.
- **The Semantic Web did not achieve broad adoption.** RDF's complexity and the difficulty of producing and consuming linked data limited its use to specialized domains.
- **REST and HATEOAS are widely misunderstood.** Most APIs described as "RESTful" do not use hypermedia links to drive application state. They use fixed URLs and out-of-band documentation.
- **IPFS has not replaced HTTP.** Content-addressing is superior in theory but requires infrastructure changes that have not happened at web scale.
- **LLMs do not yet have a link-native protocol.** They can read links embedded in HTML and text, but there is no protocol designed for LLMs as first-class consumers of linked, structured responses.

### How It Connects to Other Ideas

- **Bitcoin's hash chain.** Bitcoin links blocks through cryptographic hashes. IPFS links files through cryptographic hashes. Both use hash-based linking for integrity guarantees. The principle generalizes: any data structure can use hash-based links to become tamper-evident.
- **Capability-based security.** A link that encodes what actions are permitted (as in HATEOAS) is a form of capability: possession of the link grants the right to perform the action. This connects to capability-based security models in which authority is carried by unforgeable references.
- **OIP as the next step.** OIP (Open Invocation Protocol) combines: content-addressed storage (from IPFS) for artifacts, tamper-evident hash chains (from Bitcoin) for receipts, and links as capabilities (from HATEOAS and capability security) in responses designed for machine consumption. Each response carries links that describe what can be done next. The protocol assumes the consumer is a machine that reads, interprets, and decides.

### Sources

- Bush, Vannevar. "As We May Think." The Atlantic, 1945.
- Nelson, Ted. "Complex Information Processing: A File Structure for the Complex, the Changing and the Indeterminate." ACM, 1965.
- Engelbart, Douglas. "A Research Center for Augmenting Human Intellect." Fall Joint Computer Conference, 1968.
- Berners-Lee, Tim. "Information Management: A Proposal." CERN, 1989.
- Fielding, Roy Thomas. "Architectural Styles and the Design of Network-based Software Architectures." PhD dissertation, UC Irvine, 2000.
- Berners-Lee, Tim. "Linked Data." W3C Design Issues, 2006. https://www.w3.org/DesignIssues/LinkedData.html
- Benet, Juan. "IPFS — Content Addressed, Versioned, P2P File System." 2014.

---

## Up the tree

- [OIP root](https://miscsubjects.com/a/oip) — protocol root, zero-context entry
- [Thinker Reference hub](https://miscsubjects.com/a/oip-thinker-reference) — full hierarchy map
- [Protocol Concepts shelf](https://miscsubjects.com/a/oip-protocol-concepts) — siblings on this shelf
- [Voxel graph article](https://miscsubjects.com/a/what-is-voxel-graph) — how pages link as voxels
- [Self-describing protocol](https://miscsubjects.com/a/what-is-self-describing-protocol)

## Related on this shelf

- [What Is Autopoiesis](https://miscsubjects.com/a/what-is-autopoiesis)
- [What Is Capability-Based Security](https://miscsubjects.com/a/what-is-capability-security)
- [What Is a Capability Token](https://miscsubjects.com/a/what-is-capability-token)
- [What Is a Confused Deputy](https://miscsubjects.com/a/what-is-confused-deputy)
- [What Is Context as Cursor](https://miscsubjects.com/a/what-is-context-as-cursor)
- [What Is a Convergence Catalogue](https://miscsubjects.com/a/what-is-convergence-catalogue)
- [What Is a Falsification Surface](https://miscsubjects.com/a/what-is-falsification-surface)
- [What Is HATEOAS](https://miscsubjects.com/a/what-is-hateoas)

## Machine surfaces

- Public page: `https://miscsubjects.com/a/what-is-link-protocol-history`
- JSON article: `https://miscsubjects.com/api/articles/what-is-link-protocol-history`
- OIP ask: `https://miscsubjects.com/api/dispatch?ask=What%20Is%20the%20History%20of%20Link%20Protocols`

