Sir Tim Berners-Lee, the inventor of the worldwide web, has called on the public and politicians to "come together" to end its misuse in a letter to mark the technology's 30th anniversary.
The founder of the World Wide Web Foundation said the internet had created opportunities for good but had also become a space used by "scammers" and "given a voice to those who spread hatred, and made all kinds of crime easier to commit".
First proposed by Sir Tim as an information management system in 1989 while he was working for the European Organisation for Nuclear Research (CERN), around half of the world's population is now online.
Many of the world's largest web-based companies, such as Facebook, Twitter and Google, have come under scrutiny in recent years over data privacy issues and the rising spread of malicious and offensive content.
In his letter, Sir Tim said it would be "defeatist and unimaginative" to assume that the web could not be changed for the better given how far it has come in its first 30 years, but urged governments, organisations and the public to work together to improve the current system and make it available to everyone.
"If we give up on building a better web now, then the web will not have failed us - we will have failed the web," he said.
'Outraged and polarised'
He also called for a response to the "unintended negative consequences" of the web, which he said had led to "the outraged and polarised tone and quality of online discourse".
Sir Tim, who is due to appear at the Science Museum on Tuesday as part of the web's anniversary celebrations, concludes by labelling the need to get the rest of the world online as "urgent".
"The fight for the web is one of the most important causes of our time. Today, half of the world is online. It is more urgent than ever to ensure the other half are not left behind offline, and that everyone contributes to a web that drives equality, opportunity and creativity," he said.
"The web is for everyone and collectively we hold the power to change it. It won't be easy. But if we dream a little and work a lot, we can get the web we want."