Google Chrome is a web browser developed by Google that uses the WebKit layout engine and application framework. It was first released as a beta version for Microsoft Windows on 2 September 2008, and the public stable release was on 11 December 2008. The name is derived from the graphical user interface frame, or "chrome", of web browsers. As of December 2010, Chrome was the third most widely used browser, with 13.35% of worldwide usage share of web browsers, according to Statcounter.
In September 2008, Google released a large portion of Chrome's source code, including its V8 JavaScript engine, as an open source project entitled Chromium. This move enabled third-party developers to study the underlying source code and to help convert the browser to the Mac OS X and Linux operating systems. Google also expressed hope that other browsers would adopt V8 to improve web application performance.The Google-authored portion of Chromium is released under the permissive BSD license, which allows portions to be incorporated into both open source and closed source software programs. Other portions of the source code are subject to a variety of open source licenses. Chromium implements the same feature set as Chrome, but lacks built-in automatic updates and Google branding, and most notably has a blue-colored logo in place of the multicolored Google logo.
Chrome was assembled from 25 different code libraries from Google and third parties such as Mozilla's Netscape Portable Runtime, Network Security Services, NPAPI, as well as SQLite and a number of other open-source projects. The JavaScript virtual machine was considered a sufficiently important project to be split off (as was Adobe/Mozilla's Tamarin) and handled by a separate team in Denmark coordinated by Lars Bak at Aarhus. According to Google, existing implementations were designed "for small programs, where the performance and interactivity of the system weren't that important," but web applications such as Gmail "are using the web browser to the fullest when it comes to DOM manipulations and JavaScript", and therefore would significantly benefit from a JavaScript engine that could work faster.
Chrome uses the WebKit rendering engine to display web pages, on advice from the Android team. Like most browsers, Chrome was extensively tested internally before release with unit testing, "automated user interface testing of scripted user actions" and fuzz testing, as well as WebKit's layout tests (99% of which Chrome is claimed to have passed). New browser builds are automatically tested against tens of thousands of commonly accessed websites inside the Google index within 20–30 minutes.
Chrome includes Gears, which adds features for web developers typically relating to the building of web applications (including offline support). However, Google is phasing out Gears in favor of HTML5.
On 8 January 2009 Google introduced a new release system with three distinct channels: Stable, Beta, and Developer preview (called the "Dev" channel). Before this change there were only two channels: Beta and Developer preview. All previous Developer channel users were moved to the Beta channel. The reason given by Google is that the Developer channel builds are less stable and polished than those that Developer channel users were getting during Google Chrome's Beta period. The stable channel will be updated with features and fixes once they have been thoroughly tested in the Beta channel, and the Beta channel will be updated roughly monthly with stable and complete features from the Developer channel. The Developer channel is where ideas get tested (and sometimes fail) and can be very unstable at times. On 22 July 2010 Google announced it will ramp up the speed it will release new stable versions; they will shorten the release cycles from quarterly to 6 weeks. The faster release cycle brought a fourth channel: the "Canary" release; the name refers to using canaries in coal mines, so if a change "kills" Chrome Canary, they'll block it from the developer build. Canary will be "the most bleeding-edge official version of Chrome and somewhat of a mix between Chrome dev and the Chromium snapshot builds". Canary releases run side-by-side with any other channel; it is not linked to the other Google Chrome installation and can therefore run different synchronization profiles, themes, and browser preferences. It cannot be set as the default browser.
Chrome automatically keeps itself up to date. The details differ by platform. On Windows, it uses Google Updater, and autoupdate can be controlled via Group Policy, or users can download a standalone version that does not autoupdate. On Mac, it uses Google Update Service, and autoupdate can be controlled via the Mac OS X "defaults" system.[ On Linux, it lets the system's normal package management system supply the updates.
Google uses its Courgette algorithm to provide the binary difference of the user's current version in relation to the new version that's about to be automatically updated to. These tiny updates are well suited to minor security fixes and allow Google to push new versions of Chrome to users quickly, thereby reducing the window of vulnerability of newly discovered security flaws.
Google just launched artillery deep into territories held by Microsoft and Apple by making one of the biggest announcements in its history: The reveal of Chrome OS. And in doing so, it has declared war on the traditional desktop model.
The Cr-48 Chrome Notebook will be the first official device featuring Chrome OS. Although it’s only being released in a pilot program to beta testers, it’s very much an emissary to consumers (Google’s hopeful allies in the fight). Those of you interested in enlisting can sign up to test the device, but we’re guessing selection will be — well — selective.
The Cr-48 Chrome Notebook might not be the most powerful computing device, but that’s not the point. The device is intended for consumption, not raw processing power. Whether it performs as a consumption device remains to be seen, but if Google gets this right, Chrome OS notebooks could put a serious hurt on devices like the MacBook Air.
Source:wikipedia
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