Google is launching an open source web browser to compete with Internet Explorer and Firefox.
The browser is designed to be lightweight and fast, and to cope with the next generation of web applications that rely on graphics and multimedia.
Called Chrome, it will launch as a beta for Windows machines in 100 countries, with Mac and Linux versions to come.
"We realised... we needed to completely rethink the browser," said Google's Sundar Pichai in a blog post.
The new browser will help Google take advantage of developments it is pushing online in rich web applications that are challenging traditional desktop programs.
Google has a suite of web apps, such as Documents, Picasa and Maps which offer functionality that is beginning to replace offline software.
"What we really needed was not just a browser, but also a modern platform for web pages and applications, and that's what we set out to build," Mr Pichai, VP Product Management, wrote.
The launch of a beta version of Chrome on Tuesday will be Google's latest assault on Microsoft's dominance of the PC business. The firm's Internet Explorer program dominates the browser landscape, with 80% of the market.