Social networking site Facebook said it has acquired Parakey, a start-up run by the founders of the Firefox Web browser project.

Parakey's co-founders Blake Ross and Joe Hewitt, co-creators of the Firefox project, will join Facebook to work on the development of its technology, the company said Thursday.

Ross and Hewitt founded Parakey in early 2006 to bridge the gap between information on the Web and the desktop, Facebook said. Ross has described Parakey as an open-source "Web operating system that can do everything an OS can do," such as manipulate the contents of a hard drive. Terms of the acquisition were not disclosed.

"Blake and Joe built the Firefox Web browser and then turned to the developer community to build on top of the foundation they'd established, not unlike what we've done with Facebook Platform," said Mark Zuckerberg, founder and CEO of Facebook in a statement. "The work they've done with Firefox and Parakey and their approach to building products fit right in at Facebook."

The acquisition is the first for Facebook, which saw 26.6 million unique visitors in the U.S. in May, an 89 percent increase compared with the same month last year, according to Internet ranking company ComScore Inc. The growth followed Facebook's move in September to open the social network to the general public. Previously, it had been limited to users with a valid e-mail address from a college or university.

In May, Facebook announced it would allow developers to build new applications on top of Facebook APIs.

The acquisition signals Facebook's clear intention to become the No. 1 destination on the Web, noted Duncan Riley at the popular Web 2.0 blog TechCrunch.

"Facebook is starting to become the one-stop shop for content and interaction, be it through feeds, blog creation, image uploading and just plain ol' social networking," he wrote. "Although it's not the market leader yet, there is no argument that Facebook is rapidly growing and more and more people are using it."

Although the notion of a Web operating system lacks wide user uptake today, the increasing flow of venture capital into Web operating-system startups indicates that some people believe the Web OS eventually will become popular, Riley continued.

"Facebook knows this; what buying Parakey does is provide Facebook with a base from which it can not only become a Web OS provider, but leverage its user base to become THE Web OS provider," Riley wrote.