Three-and-a-half years after Google introduced the desktop version of its Chrome Web browser, the company has finally launched a mobile version of Chrome.

Chrome for Android Beta is now available for free through Google's Android Market. It requires phones and tablets to be running Android 4.0, also known as Ice Cream Sandwich.

"After a lot of hard work, I'm really excited to see us launch Chrome for Android Beta today," said Sundar Pichai, Google SVP of Chrome and Apps, in a Google+ post. "We set out to bring the full capability of desktop Chrome to Android and rethink the browser from the ground up for phones and tablets with a touch interface."

Google says Chrome for Android Beta is fast, though it provides no figures by which Chrome's performance can be compared to other mobile browsers, like iOS Safari or Firefox for Android.

Mobile browser speed metrics are less meaningful than desktop browser speed metrics because mobile browser performance also depends on carrier network throughput. But Chrome for Android Beta does include GPU acceleration for the HTML5 canvas element and for requestAnimationFrame, an animation API designed to work with both canvas and WebGL (presently unsupported in mobile Chrome).

[ The desktop version of Chrome saw its market share decline for the first time in January. Read Google Chrome Market Share Slip: Self-Inflicted? ]

Chrome for Android features Google's omnibox, a text entry field for both URLs and search queries, and supports tabs accessed through swipe navigation. Apple's mobile Safari maintains separate boxes for URLs and queries. It does not support tabs but does maintain previously loaded Web pages and allows them to be accessed again with two taps and a swipe.

Incognito mode is supported, though mobile devices provide so much data to cellular service providers and app makers that the private browsing mode in Chrome for Android should only be trusted so far.

Chrome for Android allows you to sign in to your Google Account. Beyond helping Google collect more information and serve more relevant ads, signing in gives users access to any browser tabs left open on a desktop version of Chrome, provided the user was signed in there too and had set up Chrome Sync (which can sync bookmarks, too). The data can flow both ways: You can bookmark pages on your phone for later reading via Chrome on your desktop computer.

Chrome for Android also can take advantage of autocomplete suggestions generated as a result of desktop Chrome usage. Google's recently announced plan to consolidate its privacy policies and make user data available across devices was designed to support this sort of desktop-to-mobile data sharing.

Though derived from Chromium, the open source project behind Chrome, Chrome for Android Beta isn't immediately available as open source code. Google says Chrome for Android will be open-sourced in phases, through Chromium, WebKit, and other relevant open source projects.

Web apps and extensions, including Adobe Flash Player, are not supported in the initial release of Chrome for Android Beta. Given the amount of effort Google has put into creating installable Web apps and nurturing its Chrome ecosystem, it's likely that Web apps and extensions will be supported in a later release. Of course, websites--Web apps minus the manifest file that enables local installation--should work just fine, app code permitting.

When extension support does arrive, don't expect to see Flash, however: Adobe announced last November that it has stopped investing in Flash for mobile and has made HTML5 the focus of its mobile development efforts. Flash on mobile devices is on its way out.

Asked whether we might see a version of Chrome for iOS, Google was non-committal but didn't rule out the possibility. "We would like to bring the same speedy, simple and seamless Chrome Web browsing experience to other mobile platforms, but have nothing to announce at this time," a company spokesperson said in an email.

Hacks of Comodo and DigiNotar exposed weakness in the Secure Sockets Layer protocol. The new Dark Reading supplement shows you what's being done to fix it. (Free registration required.)