What is Web 2.0? Features, examples and what it means for link building

Web 2.0 is the name for the web in which sites are built from what their users publish: blogs, wikis, video sites and social networks. The term was first printed in 1999 and spread through the industry after a conference in October 2004.

This page covers where the term came from, how Web 2.0 differs from Web 1.0, its key features, dated examples, its benefits and limitations, and what a Web 2.0 site means in SEO and link building.

What is Web 2.0?

Three dated sources mark the term's path into everyday use.

Darcy DiNucci used the term in "Fragmented Future", an article in Print magazine, in 1999. In it she wrote: "The first glimmerings of Web 2.0 are beginning to appear, and we are just starting to see how that embryo might develop." She was describing the web still to come, not a set of sites anyone could name yet. In her account the next web would be known by what ran underneath it rather than by how it looked: "Ironically, the defining trait of Web 2.0 will be that it won't have any visible characteristics at all."

Tim O'Reilly, founder of O'Reilly Media, carried the term to the industry. In his essay of 30 September 2005, What Is Web 2.0, he writes: "The concept of "Web 2.0" began with a conference brainstorming session between O'Reilly and MediaLive International." The first Web 2.0 conference took place in October 2004; his essay says so. He did not draw a line round the term: "Like many important concepts, Web 2.0 doesn't have a hard boundary, but rather, a gravitational core." The essay set the idea out by example, and the next section shows six of his pairings.

Tim Berners-Lee, who invented the World Wide Web, pushed back in an IBM developerWorks interview on 22 August 2006: "Web 2.0 is, of course, a piece of jargon, nobody even knows what it means." His objection had a second half, about who the web was for: "If Web 2.0 for you is blogs and wikis, then that is people to people. But that was what the Web was supposed to be all along." In his view the web had been built for people to connect from the start, and the new name added no new invention.

So the working definition on this page is by example, not by a technical standard. A Web 2.0 site is one whose pages are written, edited or uploaded by the people who use it.

Web 1.0 vs Web 2.0

O'Reilly's essay sets the two side by side in a list of pairs; six of them are below, in his words.

The pairs run from reference works and personal pages through to how pages are found. Writing in 1999, DiNucci pictured the web of that year in one sentence: "Even your grandmother can recognize a Web page by its typical brochure-like displays of Times or Arial text, eye-grabbing graphics, and highlighted hyperlinks."

Berners-Lee's counterpoint, from the IBM developerWorks interview quoted above, was: "Web 1.0 was all about connecting people."

Read together, the sources say the change was in who published the pages, more than in what the web could do.

Key features of Web 2.0

Four features run through the accounts of Web 2.0 by O'Reilly and Berners-Lee.

User-generated content

The users write the pages. Wikipedia's own About page states: "Wikipedia articles can be edited by anyone with Internet access, except in limited cases in which editing is restricted to prevent disruption or vandalism." On a Web 2.0 site the reader is also the writer. The page exists because a user put it there.

Participation and collaboration

In O'Reilly's pairs, publishing gives way to participation: the audience joins in. Blogs and wikis are Berners-Lee's own two examples of what Web 2.0 means in practice, from the IBM developerWorks interview quoted above. Participation covers writing, editing and passing material on, not only reading it.

Tagging and syndication

Two more of O'Reilly's pairs belong here. Directories gave way to tagging, which his list labels "folksonomy": users label content themselves instead of filing it under a fixed heading. A second pair sets "stickiness" against "syndication": content travels to the reader through feeds rather than waiting for the reader to visit. Both pairs are about how content is labelled and how it moves.

Web services and standard web technologies

O'Reilly's pairs also set "screen scraping" against "web services": a site offers its data to other software, not only to readers in a browser. Berners-Lee named the Web 2.0 technologies in the IBM developerWorks interview: "It means using the document object model, it means for HTML and SVG, and so on. It's using HTTP, so it's building stuff using the Web standards, plus JavaScript, of course." The feature is a site built to be used by software as well as read by people.

Examples of Web 2.0 sites

Blogger, Wikipedia, Facebook, YouTube, WordPress.com and Tumblr are six examples of Web 2.0 sites. Each date below comes from the platform's own pages.

• Blogger: launched by Pyra Labs on 23 August 1999.
• Wikipedia: created on 15 January 2001.
• Facebook: founded on 4 February 2004.
• YouTube: its domain was registered on 14 February 2005. Co-founder Chad Hurley wrote on the YouTube blog five years later: "we set out to create a place where anyone with a video camera and an Internet connection could share a story with the world."
• WordPress.com: the hosted service opened in the summer of 2005.
• Tumblr: 2007. Its founder David Karp wrote ten years later that it was launched as a side project.

Three of the six were running before or by the time of the October 2004 conference (Blogger, Wikipedia and Facebook), so the name described sites that already existed.

Benefits of Web 2.0

The first benefit is that anyone can publish. When YouTube's co-founder described the aim as letting "anyone with a video camera and an Internet connection" share a story with the world, he was describing the whole era in one clause. The person with something to say could put it online themselves, on a site that handled the hosting and the software. Opening an account was enough.

The second benefit is pooled knowledge. Wikipedia is written by its readers: anyone with Internet access can write and correct most of its articles. An answer written once stays on the page for the next reader. The encyclopaedia is the clearest case, and the same pattern runs through blogs, wikis and video sites.

The third benefit is the one that matters for a business. A hosted platform gives you a page of your own that you can publish in an afternoon, with your words and your links. The final section of this page returns to what that means in practice.

Limitations of Web 2.0

The main challenges of Web 2.0 are a term with no fixed boundary, content whose accuracy depends on who wrote it, and the security of applications that accept input from users.

The term has no fixed boundary

O'Reilly's essay said Web 2.0 has no hard boundary, and Berners-Lee called the term a piece of jargon. Two people can mean different sites by Web 2.0: one means blogs and wikis, another means social networks and video sites. The examples above show why, since the list spans a blog platform, an encyclopaedia, a social network and a video site. Any use of the term has to say which sense it carries.

Content depends on who wrote it

When users write the pages, accuracy depends on the writer and on how the site checks edits. Wikipedia's About page says editing is restricted in limited cases, which shows one Web 2.0 site checking what its users write. Each page has to be read with its writer in mind.

Security of Web 2.0 applications

Sites that accept input from users have to handle that input securely. OWASP, the Open Worldwide Application Security Project, defines two classes of attack that apply here. The first is cross-site scripting: "Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted websites." The second is cross-site request forgery: "Cross-Site Request Forgery (CSRF) is an attack that forces an end user to execute unwanted actions on a web application in which they’re currently authenticated." Both are jobs for the people who build the application.

What Web 2.0 means for SEO and link building

In SEO, "Web 2.0 site" (or "Web 2.0 property") has a narrower meaning: a hosted platform where anyone can open an account and publish a page, such as a blog on WordPress.com, Blogger or Tumblr. A "Web 2.0 link" or "Web 2.0 backlink" is a link on a page you publish there yourself. That is a usage note: it is how link builders use the term. A link of this kind sits among the wider types of backlinks a site can carry, and the rest of this section stays with that usage.

Links were part of the idea from the start. O'Reilly's 2005 essay states: "Hyperlinking is the foundation of the web." The same essay, writing about bloggers, says: "First, because search engines use link structure to help predict useful pages, bloggers, as the most prolific and timely linkers, have a disproportionate role in shaping search engine results." That is his sentence from 2005, about the bloggers of that moment.

The platforms' own pages describe the mechanics their editors offer. WordPress.com's support page on links describes a per-link setting: "Check the box next to Mark as nofollow." and "This adds a rel="nofollow" HTML parameter to your link." Blogger's help page has the same kind of setting: "Check the box next to Add ‘rel=nofollow’ attribute." Tumblr's help page sets limits per post: "The maximum number of inline links is 100." On these platforms the person who publishes the page chooses the links, and on WordPress.com and Blogger they can set the attribute on each one. Our page on dofollow and nofollow explains the two attributes.

One pattern of use is the second tier: some link builders point hosted pages at a page that already links to them. Our page on tiered link building defines the arrangement and sets out the evidence. Links from profiles on social sites are a related pattern, covered on our page about social media link building.

A writer who publishes as Burk on Substack posted their own Google Search Console figures on 29 September 2026 for the same writing published on two hosted platforms, each on its own custom domain, over 90 days: "In that window Medium got about 4,200 clicks from 380,000 impressions. Substack got about 700 clicks from 290,000 impressions." Burk's own caveat came with the figures: "this is one writer, one niche, 90 days." The account is about search clicks to pages on hosted platforms, not about links.

A Web 2.0 page is one you publish and can open and check yourself. Our Curated Links and Guest Posts are links on sites that someone else owns: a Curated Link is added to an article that is already published, and a Guest Post is a new article of 750 words or more. Because the page is not ours or yours, we check it after publication: the page is live, the link is in the body copy, the anchor and target URL match the order and the page is indexable, and only then is the URL reported to the dashboard. That check is part of the quality assurance applied to every order. Links on sites that other people own sit within off-page SEO as a whole, which our overview covers.

Frequently asked questions

What is Web 2.0?

Web 2.0 is the name for the web in which sites are built from what their users publish: blogs, wikis, video sites and social networks. The term was first printed in 1999 and spread through the industry after a conference in October 2004.

What is the main difference between Web 1.0 and Web 2.0?

The difference is who publishes. A Web 1.0 page was published by the site's owner for readers, while a Web 2.0 page is written, edited or uploaded by the people who use the site. Tim O'Reilly's 2005 essay on Web 2.0 pairs Britannica Online with Wikipedia to make the point.

What are some examples of user-generated content in Web 2.0?

Wikipedia articles, blog posts on Blogger, WordPress.com and Tumblr, videos on YouTube and posts on Facebook are all user-generated content. In each case the page exists because a user published it rather than the site's owner.

What are the key features of Web 2.0?

The four key features of Web 2.0 are user-generated content, participation and collaboration, tagging and syndication, and web services built on standard web technologies. The first three describe readers taking part; the fourth describes sites that offer their data to other software.

What is the main problem of Web 2.0?

Content is written by users, so its accuracy depends on the writer and on the checks the site applies. Applications that accept user input also have to handle that input securely.

What are the security concerns of Web 2.0 applications?

OWASP defines two classes of attack for applications that take input from users. Cross-site scripting injects malicious scripts into pages that other users load. Cross-site request forgery makes a signed-in user run actions they did not choose.

What is a Web 2.0 backlink?

A Web 2.0 backlink is a link on a page you publish yourself on a hosted platform such as WordPress.com, Blogger or Tumblr. You choose the page's words and its links.