Governments and companies should limit the snooping they do on web users.
So said Sir Tim Berners-Lee, inventor of the world wide web, who said that growing oversight of browsing could have a pernicious effect.
A greater part of the value of the web lay in the lack of constraints on what people could do with it.
He also warned that attempts to censor what people could say or what they could do online were ultimately doomed to failure.
"When you use the internet it is important that the medium should not be set up with constraints," he said.
The internet, said Sir Tim, should be like a blank piece of paper. Just as governments and companies cannot police what people write or draw on that sheet of paper so they should not be restricted from putting the web to their own uses.
"The canvas should be blank," he said
While governments do need some powers to police unacceptable uses of the web; limits should be placed on these powers, he said.
If people know that where they go online and the terms they look for are under scrutiny it could have all kinds of pernicious effects, he warned.
Repressive regimes, such as China and Iran, that work hard to limit what people can do online would struggle to maintain that control over time, he said.