A browser isn’t just a tool for looking at websites. It has the power to shape the experience of being online. A new browser, Rockmelt, is built to show the Web through the prism of your online contacts. Social features literally frame every page the user views, meaning that every page view is surrounded by tools that let users share it with social networks, see which friends are online, and get updates from social networks.

The browser launched in preview form this week and garnered a slew of attention, in part because of the Netscape pedigree of its backers. It’s nicely designed, and it succeeds at making it easy to connect with people while browsing. However, Rockmelt relies heavily on existing products from Facebook and Google. This could leave it vulnerable if either of those companies decides to move in on its territory.

Rockmelt has good ideas behind it, but none of them seem to be entirely its own. The software is essentially a Facebook application built on top of the open-source version of Google’s Chrome browser. As such, it has all the beneficial features of Chrome—it is fast, handles multiple tabs well, and is well-suited to running Web applications in the browser.

To get started using Rockmelt, you first need to sign in to Facebook. This allows the browser to pull in your list of Facebook friends (which appears on the left edge of the screen), and lets users post to Facebook at any time and easily share pages on Facebook.

The integration with Facebook is, for the most part, smooth and intuitive. A “share” button placed prominently between the URL bar and search bar lets a user comment on and post a link to Facebook. If the user also adds a Twitter account to Rockmelt, that button can share content through that site as well.

Other features are a little more confusing. For example, Rockmelt tracks friends in its left “edge.” The view of online friends works well: you can quickly pull up profile information on the people who appear there, send them messages, or start a chat through Facebook. However, it also has a “favorite friends” view, which is harder to use. Friends have to be selected manually from a list of all friends, and they seem to appear in that panel in the order they were selected, rather than being shuffled alphabetically or based on who is online.

It’s also possible to confuse the browser about whether you’re logged in to Facebook. I found that logging in and out of the website sometimes disrupted the functioning of Rockmelt’s social features.