Friday, April 6, 2012


Safari is a web browser developed by Apple Inc. and included with the Mac OS X and iOS operating systems. First released as a public beta on January 7, 2003 on the company's Mac OS X operating system, it became Apple's default browser beginning with Mac OS X v10.3 "Panther". Safari is also the native browser for iOS. A version of Safari for the Microsoft Windows operating system, first released on June 11, 2007, supports Windows XP, Windows Vista, and Windows 7. According to Net Applications, Safari accounted for 62.17 percent of mobile web browsing traffic and 5.43 percent of desktop traffic in October 2011, giving a combined market share of 8.72 percent. Safari is the fourth most popular web browser, behind Internet Explorer (49.59 percent), Mozilla Firefox (21.20), and Google Chrome (16.60).

History and development
Until 1997, Apple Macintosh computers were shipped with the Netscape Navigator and Cyberdog web browsers only. Internet Explorer for Mac was later included as the default web browser for Mac OS 8.1 and onwards, as part of a five year agreement between Apple and Microsoft. During that time, Microsoft released three major versions of Internet Explorer for Mac that were bundled with Mac OS 8 and Mac OS 9, though Apple continued to include Netscape Navigator as an alternative. Microsoft ultimately released a Mac OS X edition of Internet Explorer for Mac, which was included as the default browser in all Mac OS X releases from Mac OS X DP4 until Mac OS X v10.2.
Safari 1
On January 7, 2003, at Macworld San Francisco, Steve Jobs announced that Apple had developed their own web browser, called Safari. It was based on Apple's internal fork of the KHTML rendering engine, called WebKit.[9] Apple released the first beta version for OS X that day. A number of official and unofficial beta versions followed, until version 1.0 was released on June 23, 2003. Initially only available as a separate download for Mac OS X v10.2, it was included with the Mac OS X v10.3 release on October 24, 2003 as the default browser, with Internet Explorer for Mac included only as an alternative browser. 1.0.3, released on August 13, 2004 was the last version to support Mac OS X v10.2, while 1.3.2, released on January 12, 2006 was the last version to support Mac OS X v10.3. However, 10.3 received security updates through 2007.
Safari 2
In April 2005, Dave Hyatt, one of the Safari developers at Apple, documented his progress in fixing specific bugs in Safari, thereby enabling it to pass the Acid2 test developed by the Web Standards Project. On April 27, 2005, he announced that his development version of Safari now passed the test, making it the first web browser to do so.
Safari 2.0 was released on April 29, 2005 as the only web browser included with Mac OS X v10.4. This version was touted by Apple as possessing a 1.8x speed boost over version 1.2.4, but did not yet include the Acid2 bug fixes. The necessary changes were not initially available to end-users unless they downloaded and compiled the WebKit source code themselves or ran one of the nightly automated builds available at OpenDarwin.org. Apple eventually released version 2.0.2 of Safari, which included the modifications required to pass Acid2, on October 31, 2005.
In June 2005, after some criticism from KHTML developers over lack of access to change logs, Apple moved the development source code and bug tracking of WebCore and JavaScriptCore to OpenDarwin.org. WebKit itself was also released as open source. The source code for non-renderer aspects of the browser, such as its GUI elements, remains proprietary.
The final stable version of Safari 2, Safari 2.0.4, was released on January 10, 2006 for Mac OS X. It was only available as part of Mac OS X Update 10.4.4. This version addresses layout and CPU usage issues, among others. Safari 2.0.4 was the last version to be released exclusively on Mac OS X.
Safari 3
On January 9, 2007, at Macworld SF, Jobs announced Apple's iPhone, which would use a mobile version of the Safari browser.
On June 11, 2007, at the Apple Worldwide Developers Conference, Jobs announced Safari 3 for Mac OS X v10.5, Windows XP, and Windows Vista. During the announcement, he ran a benchmark based on the iBench browser test suite comparing the most popular Windows browsers, hence claiming that Safari was the fastest browser. Later third-party tests of HTTP load times would support Apple's claim that Safari 3 was indeed the fastest browser on the Windows platform in terms of initial data loading over the Internet, though it was found to be only negligibly faster than Internet Explorer 7 and Mozilla Firefox when loading static content from local cache.
The initial Safari 3 beta version for Windows, released on the same day as its announcement at WWDC 2007, had several known bugs and a zero day exploit that allowed remote execution. The addressed bugs were then corrected by Apple three days later on June 14, 2007, in version 3.0.1 for Windows. On June 22, 2007, Apple released Safari 3.0.2 to address some bugs, performance issues and other security issues. Safari 3.0.2 for Windows handles some fonts that are missing in the browser but already installed on Windows computers, such as Tahoma, Trebuchet MS, and others.
The iPhone was formally released on June 29, 2007. It includes a version of Safari based on the same WebKit rendering engine as the desktop version, but with a modified feature set better suited for a mobile device. The version number of Safari as reported in its user agent string is 3.0, in line with the contemporary desktop versions of Safari.
The first stable, non-beta release of Safari for Windows, Safari 3.1, was offered as a free download on March 18, 2008. In June 2008, Apple released version 3.1.2, addressing a security vulnerability in the Windows version where visiting a malicious web site could force a download of executable files and execute them on the user's desktop.
Safari 3.2, released on November 13, 2008, introduced anti-phishing features and Extended Validation Certificate support. The final version of Safari 3 is 3.2.3, released on May 12, 2009.
Safari 4
On June 2, 2008, the WebKit development team announced SquirrelFish, a new JavaScript engine that vastly improves Safari's speed at interpreting scripts. The engine is one of the new features in Safari 4, released to developers on June 11, 2008. The new JavaScript engine quickly evolved into SquirrelFish Extreme, featuring even further improved performance over SquirrelFish, and was eventually marketed as Nitro. A public beta of Safari 4 was released on February 24, 2009, with new features such as the Top Sites tool (similar to Opera's Speed Dial feature), which displays the user's most visited sites on a 3D wall. Cover Flow, a feature of Mac OS X and iTunes, was also implemented in Safari. In the public beta versions, tabs were placed in the title bar of the window, similar to Google Chrome. The tab bar was moved back to its original location, below the URL bar, in the final release. The Windows version adopted a native Windows theme, rather than the previously employed Mac OS X-style interface. Also Apple removed the blue progress bar located in the address bar (later reinstated in Safari 5). Safari 4.0.1 was released for Mac on June 17 and fixed problems with Faces in iPhoto '09. Safari 4 in Mac OS X v10.6 "Snow Leopard" has 64-bit support, which can make JavaScript loading up to 50% faster. It also has built-in crash resistance unique to Snow Leopard; crash resistance will keep the browser intact if a plug-in like Flash player crashes, such that the other tabs or windows will be unaffected. Safari 4.0.4, released on November 11, 2009 for both OS X and Windows, further improves JavaScript performance.
Safari was one of the twelve browsers offered to EU users of Microsoft Windows in 2010. It is also one of the five browsers displayed on the first page of browser choices along with Chrome, Firefox, Internet Explorer and Opera. 
Safari 5
Safari displaying its Reader view of a Wikipedia article.
Apple released Safari 5 on June 7, 2010, featuring the new Safari Reader for reading articles on the web without distraction (based on Arc90's Readability tool), and a 30 percent Javascript performance increase over Safari 4. Safari 5 includes improved developer tools and supports more than a dozen new HTML5 technologies, focused on interoperability. With Safari 5, developers can now create secure Safari Extensions to customize and enhance the browsing experience. Apple also re-added the progress bar behind the address bar in this release. Safari 5.0.1 enabled the Extensions PrefPane by default; previously, users had to enable it via the Debug menu.
Apple also released Safari 4.1 concurrently with Safari 5, exclusively for Mac OS X Tiger. The update included the majority of the features and security enhancements found in Safari 5. It did not, however, include Safari Reader or Safari Extensions. Together with Mac OS X 10.7 Lion, Apple released Safari 5.1 for both Windows and Mac on July 20, 2011, with the new function 'Reading List' and a faster browsing experience. Apple simultaneously released Safari 5.06 for Mac OS X 10.5 Leopard, excluding Leopard users from the new functions in Safari 5.1. On 16th March 2012, Apple released a developer preview of Safari 5.2 which will (when released) allow users to 'sync' their open tabs with any iOS or other OS X device running the latest software. The feature, named only as iCloud Tabs, is expected to be released with the upcoming OS X Mountain Lion in late summer 2012. 

WebKit2
On April 9, 2010, Apple announced WebKit2. This was integrated into Safari as of version 5.1.
"WebKit2 is designed from the ground up to support a split process model, where the Web content (JavaScript, HTML, layout, etc) lives in a separate process," wrote Apple developer Anders Carlsson to WebKit's public mailing list on April 8, 2010. "This model is similar to what Google Chrome offers, with the major difference being that we have built the process split model directly into the framework, allowing other clients to use it."
The "process split" model to which Carlsson refers is the architecture that enables processes spawned by the browser, including add-ons and Web apps, to be run as separate processes in the operating system while still being protected by the browser's sandbox. Google's Chromium team developed the first such model in working form for its Chrome browser. 

Features
Safari offers numerous features, including:
Safari's Web Inspector, showing the DOM tree for this page.
On Mac OS X, Safari is a Cocoa application. It uses Apple's WebKit for rendering web pages and running JavaScript. WebKit consists of WebCore (based on Konqueror's KHTML engine) and JavaScriptCore (originally based on KDE's JavaScript engine, named KJS). Like KHTML and KJS, WebCore and JavaScriptCore are free software and are released under the terms of the GNU Lesser General Public License. Some Apple improvements to the KHTML code are merged back into the Konqueror project. Apple also releases additional code under an open source 2-clause BSD-like license.
It includes a built-in web feed aggregator that supports the RSS and Atom standards. Other features include Private Browsing (a mode in which no record of information about the user's web activity is retained by the browser), the ability to archive web content in the proprietary Webarchive format, the ability to e-mail complete web pages directly from a browser menu, and the ability to search bookmarks.
New features in Safari 4
Beginning with Safari 4, the address bar has been completely revamped:
Safari 4 on Windows XP
  • The blue inline progress bar is replaced with a spinning bezel and a loading indicator attached to it.
  • The button to add a bookmark is now attached to the address bar by default.
  • The reload/stop button is now superimposed on the right end of the address bar.
These modifications make Safari on Mac OS X and Windows look more similar to Safari on iPhone than previous versions.
Safari 4 also includes the following new features:
  • Completely passes the Acid3 standards test
  • Cover Flow browsing for History and Bookmarks
  • Improved developer tools, including Web Inspector, CSS element viewing, JavaScript debugger and profiler, offline table and database management with SQL support, and resource graphs
  • Nitro JavaScript engine that executes JavaScript up to eight times faster than Internet Explorer 8 and more than four times faster than Firefox 3
  • Native Windows look on Windows (Aero, Luna, Classic, etc., depending on OS and settings) with standard Windows font rendering and optional Apple font rendering
  • Support for CSS image retouching effects
  • Support for CSS Canvas
  • Speculative loading, where Safari loads the documents, scripts, and style information that are required to view a web page ahead of time
  • Support for HTML5
  • Top Sites, which displays up to 24 thumbnails of a user's most frequently-visited pages on startup
New features in Safari 5
Safari 5 includes the following new features:
  • Full-text search through the browser history
  • Safari Reader, which removes formatting and ads from webpages
  • Smarter address field, where the address bar autocomplete will match against titles of web page in history or bookmarks.
  • Extensions, which are add-ons that customize the web browsing experience.
  • Improved support for HTML5, including full screen video, closed caption, geolocation, EventSource, and WebSocket.
  • Improved Web Inspector.
  • Faster Nitro Javascript Engine.
  • DNS prefetching, where Safari finds links and looks up addresses on the web page ahead of time.
  • Bing search.
  • Improved graphics hardware acceleration on Windows.
Additionally, the blue inline progress bar has returned to the address bar, in addition to the spinning bezel and loading indicator introduced in Safari 4. Top Sites view now has a button to switch to Full History Search. Other features include Extension builder for developers of Safari Extensions, which are built using web standards such as HTML5, CSS3, and Javascript.
iOS-specific features
Safari 4.2 on the iPhone and iPod Touch in the Landscape view. The icon at the bottom center changed because of AirPrint.
Safari 5.1 on the iPad 2 in Landscape view.
iOS-specific features for Safari enable:
  • Bookmarking links to particular pages as "Web Clip" icons on the Home screen.
  • MDI-style browsing (with up to 8 pages open concurrently, limited by cache storage).
  • Opening specially-designed pages in full-screen mode.
  • Pressing on an image for 3 seconds to save it to the photo album.
  • Support for HTML5 new input types.
New in iOS 4.2
  • Find feature built into search box.
  • Ability to print the current webpage using AirPrint.[46]
New in iOS 4.3
  • Integration of the Nitro JavaScript engine for faster page loads. This feature was expanded to all applications in iOS 5.0.
New in iOS 5
  • True tabbed browsing, similar to the desktop experience, only for iPads.[47]
  • Reading List, a bookmarking feature that allows tagging of certain sites for reading later, which syncs across all Safari browsers (mobile and desktop) via Apple's iCloud service.
  • Reader, a reading feature that can format text and images from a web page into a more readable format, similar to a PDF document, while stripping out web advertising and superfluous information.
  • Private browsing, like in most desktop browsers a feature that doesn't save your cookies and history.
System requirements
Safari 5.1 requires either a Mac running Mac OS X v10.6.8, or a PC running Windows XP SP2, Windows Vista, or Windows 7. Official minimum hardware requirements for Windows state a 500 MHz Pentium processor with 256 MB of RAM for Windows. Cover Flow and Top Sites require a graphics card that is Quartz Extreme-compatible with 16 MB or more video memory for Mac or DirectX 9-compatible with 64 MB or more video memory for Windows.
Safari 5.0.6 requires a Mac running on Mac OS X 10.5.8.[49]
64-bit builds
The version of Safari included in Mac OS X v10.6 is now compiled for 64-bit architecture. Apple claims that running Safari in 64-bit mode will increase rendering speeds by up to 50%.

Criticism
Distribution through Apple Software Update
An earlier version of Apple Software Update (bundled with Safari, QuickTime, and iTunes for Microsoft Windows) selected Safari for installation from a list of Apple programs to download by default, even when a pre-existing installation of Safari was not detected on a user's machine. John Lilly, CEO of Mozilla, stated that Apple's use of its updating software to promote its other products was "a bad practice and should stop." He argued that the practice "borders on malware distribution practices" and "undermines the trust that we're all trying to build with users." Apple spokesman Bill Evans responded to Lilly's statement, saying that Apple was only "using Software Update to make it easy and convenient for both Mac and Windows users to get the latest Safari update from Apple." Apple also released a new version of Apple Software Update that puts new software in its own section, though still selected for installation by default. In a newer update, Apple Software Update no longer selected new installation items in the new software section by default (as of late 2008).
On September 22, 2009, Apple once again checked "Install Safari 4" as a default setting with their update to iTunes v9.0.1.
Browser exploits
In the PWN2OWN contest at the 2008 CanSecWest security conference in Vancouver, British Columbia, a successful exploit of Safari caused Mac OS X to be the first OS to fall in a hacking competition. Participants competed to find a way to read the contents of a file located on the user's desktop, in one of three operating systems: Mac OS X Leopard, Windows Vista SP1, and Ubuntu 7.10. On the second day of the contest, when users were allowed to physically interact with the computers (the prior day permitted only network attacks), Charlie Miller compromised Mac OS X through an unpatched vulnerability of the PCRE library used by Safari. Miller had been aware of the flaw prior to the beginning of the conference and worked to exploit it unannounced, as is the common approach in these contests. The exploited vulnerability was patched in Safari 3.1.1, among other flaws.
In the 2009 PWN2OWN contest, Charlie Miller performed another successful exploit of Safari to hack into a Mac. Miller again acknowledged that he had advance knowledge of the security flaw prior to the competition, and had done considerable research and preparation work on the exploit. Apple released a patch for this exploit and others on May 12, 2009 with Safari 3.2.3.
Malware blocking
In recent analysis, the stable version of Safari blocked 13% of malicious URLs. In contrast, Internet Explorer 9 blocked 92% of malware with its URL-based filtering, and a full 100% with Application-based filtering enabled. Internet Explorer 8, in second place, blocked 90% of malware.
Software license agreement
The original software license agreement for Safari on Windows was unusually restrictive for several months reading in part:
This License allows you to install and use one copy of the Apple Software on a single Apple-labeled computer at a time.
As most personal computers running Windows are not Apple-labeled computers, it was impossible for most Windows users to use the software and abide by the license agreement, with the exception of Intel-based Mac computers running Windows. Within hours of the story breaking about the long-unnoticed anomaly, Apple changed the agreement as posted on their website to read:
This license allows you to install and use one copy of the Apple Software on each computer owned or controlled by you.
However, the Safari installer was not immediately updated and still contained the old license.[64] Later installers include corrected copies of the license.
 



 




  



 



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