Keeping Up With... Web Annotation

This edition of Keeping Up With... was written by Lorena O’English.  

Lorena O’English is the Social Sciences and Government Documents Librarian at Washington State University, email:

What is Web Annotation? 

As librarians, we are very familiar with annotated books and articles – documents with highlighted passages, notes in the margins, and maybe a few cryptic drawings included. Web annotation takes those practices and makes them available to use in marking up web pages and other web documents in such a way that when we return to those online documents, the annotations are still there – persistent – and are perhaps joined by new annotations by others, or even responses to annotations that we originated. These annotations are not actually saved on the web document however; instead they reside on the servers of the annotation service being used, and exist as an overlay that can only be seen by other annotators, depending on whether the annotation was made public, group-only, or private.
Web annotation may be new to us, but it is not new to the Web. Marc Andreessen, one of the founders of early web browsing, noted that it was actually part of the precursor to Netscape but was eventually left out of Netscape due to server issues. Over the years many companies have tried to provide some sort of annotation capability for the web. Annotation service Hypothesis has created a list of over 50 web annotation services, many now defunct, available from the early 1990s to current.  In addition, many academic publishing platforms allow annotation within their platforms, natively or through use of partnerships. Many of these are limited, however, either by annotating PDFs and not online web documents and/or having highlighting and/or sticky note functionality that is based on screenshotting, or that can only be seen by the annotator. The three services described below are examples of true web annotation tools that allow the user to work in their browser to annotate distinct passages on dynamic web pages that are anchored to annotations, and share these annotations with others (each also includes PDF annotation functionality as well).  

Three Web Annotation Services

Hypothesis was started in 2011 as a non-profit. It is open source, and the organization has focused on open and social annotation and has created a worldwide annotation community, including partnerships with publishers, preprint servers, and other information providers. 

  • Hypothesis has a Chrome extension and bookmarklets for other browsers like Firefox. Hypothesis positions its services for a wide range of users, including scholars, teachers, students, journalists, and the publishing community in order to “hold discussions, read socially, organize your research, and take personal notes.“
  • Annotations appear on a right-side panel on the annotated page, and can be private, public, or limited to a specified group. Annotations have formatting options including bullets, and can include links, images, videos, equations, and more, and can be attached to a specific passage with an anchor or made as a page note. All annotations are linked on the user’s Hypothesis account page.
  • Each annotation can be tagged, providing robust opportunities for connecting annotations across documents. They can be responded to through threaded discussion on the annotated page if they have been made visible to a specific group or the public, and responses can also include formatting, links, etc.  

From the beginning Hypothesis has been involved in a multi-year attempt to develop partnerships and standards for browser-based open annotation through the Annotating All Knowledge project (tagline: “A new open layer is being created over all knowledge”) and through its work with the World Wide Web Consortium (W3C).  

  • In early 2017, after years of work, the Web Annotation Working Group of W3C came out with recommendations and working group notes providing a “set of specifications for an interoperable, sharable, distributed Web Annotation architecture.“
  • Interoperability ensures that annotations will have a common architectural framework, and will be discoverable, shareable, and portable across platforms. This is in line with accepted scholarly communication frameworks such as the Invest in Open Infrastructure initiative.  

Diigo is a multifunctional social bookmarking site that also provides the ability to annotate webpages through the Diigo Web Collector extension (Firefox and Chrome).  

  • Annotations can be “floating” or can be anchored to a particular passage.  Annotations can be private or shared with specified group(s); group members can reply but only within Diigo, not on the annotated webpage. A unique service allows Kindle annotations (highlights and notes) to be sent to a user’s Diigo library.   
  • Diigo’s annotations are social, but not open; it uses a proprietary standard and has shown no interest so far in participating in the development or implementation of open W3C standards.  
  • Full functionality also requires a paid account, although free teacher accounts provide a substantial upgrade from the free basic account. Diigo has generally done more outreach to the K-12 community than to the higher education community. 

F1000 Workspace is part of the Faculty of 1000 ecosystem which was created by and for life science researchers, although the Workspace can be used for work in any academic discipline. 

  • F1000 Workplace is an reference management tool with the added capabilities of annotating PDFs and web pages with highlights and text notes with the F1000 Annotator extension; annotations can be private or shared with a specified project group, and can be replied to in the F1000W application, although not on the actual web page.  
  • Like Diigo, F1000W annotations are proprietary and not open. F1000W requires a subscription after the initial trial period, but even after the trial is over users can continue to use the extension’s annotation tools for the three projects they can create during the trial.  

The Value of Web Annotation 

Persistent and open annotations have the potential for providing significant value for teaching, learning, and research in all scholarly disciplines.  

  • Annotation makes it easier to keep track of what you read by enabling notes and critiques attached via anchors that can later be searched by text or tag.  
  • Groups of students and/or researchers can collaboratively annotate a document (scholarly or popular), learning from and engaging with each other in a conversation that they can return to over time.  
  • Researchers can engage with disciplinary research – Staines and Martone note that commenting capability is slowly disappearing from the scholarly web, and open annotation offers a way to make that “community feedback” happen in a way that provides more and richer affordances then the original commenting capability and creates more value for the larger scholarly record [1]. It also offers interesting possibilities for peer review that are being implemented by some of Hypothesis’ partners.  

Web annotation is not without its detractors, however.  The music annotation site Genius provided a general web annotation functionality, dubbed News Genius, between 2015 and 2016, and its use led to concerns and accusations about intellectual property rights (do people have the right to annotate your site, potentially distorting your work?), privacy, and instances of harassment and trolling and more that replicated some of the issues raised against earlier web annotation tools such as Third Voice (1999-2001). Tools such as Hypothesis, Diigo and F1000W are more tied to a professional identity and less likely to be used that way, however, but annotations can also be blocked through the use of a script that can be inserted in a web page’s coding. 
Other concerns include the potential of spam or malware showing up in annotations (although provider  security measures reduce the likelihood of any embedded malware), as well as structural questions about annotations that are “orphaned” when the text they were anchored to is taken down from the web.

How Can Librarians Use Web Annotation?

Librarians can use web annotation services for their own use, but they also are a powerful tool to use in working with students and faculty. Anchor linking allows the source evaluation process to be more focused, for example, while instructors may use group annotation to generate discussion and consensus among students. Hypothesis has been used as a fact-checking tool in the Digital Polarization Initiative, helping students evaluate claims, for example. Graduate students and other researchers working on literature reviews are an excellent potential audience. Faculty may be interested in the ability to extend collaborative discourse about an article. As more members of the academic community integrate it into their individual and group workflows and discover new and creative ways to use it, web annotation has the potential for being a strong part of the academic librarian toolkit.


[1] Staines, Heather and Maryann E. Martone, “Community Feedback on Scholarly Content: Why It Is Important and Why It Should Be Preserved,” Insights 31(2019): 13.

Recommended Reading

Digital Annotations with – a free online course. .
Farber, Matthew. “Social Annotation in the Digital Age,” Edutopia, July 22, 2019,