Global action is required to tackle the web's "downward plunge to a dysfunctional future", its inventor Sir Tim Berners-Lee has told the BBC.
Sir Tim's vision was "at once utopian and realistic", said Jonathan Zittrain, author of The Future of the Internet and How to Stop It.
It rested on the idea that a free and open web would empower its users, rather than reduce them to simply being consumers, he explained.
"I see Tim's letter not only as a call to build a better web, but to rededicate ourselves to the core principles it embodies," he told the BBC.
Those principles, he said, included universality of access and transparency - the ability to see and understand how web applications work.