World Wide Web Consortium director Berners-Lee explained to attendees of security vendor McAfee's Mpower Cybersecurity Summit that the original idea of the World Wide Web was Utopian in the sense that it gave power to individuals. Blogs and links formed "a social machine" that unlike traditional media such as broadcast TV was able to support a long tail of content that was relevant to niche audiences.

"The value of the Web was in the small and medium people," he said.

But today, hardly anyone runs their own web server; they are on Facebook instead. So algorithms — not the human-curated links of the early days — determine what people see, and their personal data is used to direct advertising. "So there are some issues" with the web, especially as consolidation tends to reduce innovation.

In 2009, Berners-Lee began a push for data to be made available in machine-readable form, rather than just as human-oriented formats such as PDF.

While government data should be freely available — "it's obvious it generates lots of value," he said — an individual's personal data can sit on various places on the spectrum from completely private to completely public. Even if they want to keep very tight control over certain pieces of data, there are situations where sharing it with exactly the right people can make life better.

Being able to share calendars with one's spouse can be a marriage saver, he suggested. And while it may be appropriate to store different calendars (eg, work and personal) in separate systems, it needs to be possible to display them together.

Other examples of data that might be shared very selectively include bank transactions and health and fitness data.

As previously reported,these ideas led to the Solid project, "a proposed set of conventions and tools for building decentralised social applications based on Linked Data principles." Solid provides for true data ownership and separates applications from the storage of such data. It also provides one API for those applications to access data in any compliant store, including any that you operate for yourself.

"It's about empowering through data," he said. "Collaboration thrives when you've got good control of your data."

There is "huge value in the middle" of the spectrum between fully public and fully private data, he suggested. "We get the long tail back."

A user might choose to store their most important photos (eg, wedding photos) in a store run by their bank because it promises very high availability, reliability and security, while the others are stored elsewhere. Or they might share information relating to a planned home renovation with a particular architect.

So Solid provides users with control over their data, along with APIs that allow applications from multiple sources to access data spread across multiple stores. Together, these features form a platform for a new generation of collaborative software.

A Solid application should be in the service of the user, he said, so it should surprise users with benefits, not ambush them with advertising or through the surreptitious use of their data. In this context, Berners-Lee recalled that he stopped using Quicken to prepare his tax returns when the program started trying to sell him insurance.

Users do not have to start from scratch when they adopt Solid. The Data Transfer Project backed by Facebook, Google, Microsoft and Twitter is intended to make it practical to transfer data from one provider to another. It confirms the idea that users own their own data, Berners-Lee said, and "that is brilliant for Solid." Although the Data Transfer Project is still a work in progress, he has already used the API to transfer data from Google to Solid.

As well as starting Solid, Berners-Lee co-founded Inrupt, a company that's working to make Solid a reality. You can get a Solid pod (data store) from Inrupt as an alternative to running your own server, but he admits the service is not yet ready for prime time.

The writer attended McAfee's Mpower Cyberecurity Summit as a guest of the company.