USER EXPERIENCE Availability on Operating SystemsDesktop operating systems Adobe Flash Player exists for a variety of desktop operating systems, including Windows, Mac OS 9/X, Linux, Solaris, HP-UX, OS/2, QNX, BeOS, and IRIX. Flash as a format has become widespread on the desktop market; one estimate is that 95% of PCs have it, while Adobe claims that 98 percent of U.S. web users and 99.3 percent of all Internet desktop users have installed the Flash Player with 92 to 95% (depending on region) having the latest version. Numbers vary depending on the detection scheme and demographics.
As of May 2011, users with computers that usethe PowerPC G5 processor are not able to view Flashcontent from within some site (e.g. Facebook) as itrequires the latest upgrade of Adobe Flash player whichis not compatible with this processor architecture. Dueto this issue, video content hosted on such sites can nolonger be played on devices using the G5 processor.
Mobile operating systems Adobe Flash Player exists for a variety ofmobile operating systems, including Android (sinceversion 2.2), Pocket PC/Windows CE, QNX (e.g.on BlackBerry PlayBook), Symbian, Palm OS, andwebOS (since version 2.0).There is no Adobe Flash Player for iOS devices(iPhone, iPad and iPod Touch). The iPhone accountsfor more than 60% of global smartphone web trafficand the iPod touch makes up more than 95% of"mobile Internet device" traffic. Thishurts Adobes ability to market Flash as a ubiquitousmobile platform. Flash content can be made to runon iOS devices in a variety of ways:
Flash content can be bundled inside an Adobe AIRapp, which will then run on iOS devices. (Apple didnt allowthis for a while, but they relaxed those restrictions inSeptember 2010.) On March 8, 2011, Techradar reported that Adobeprovides an experimental server side tool (Wallaby) to convertFlash programs (as far as possible) to HTML5 code, thusallowing iOS devices to display the content.If the content is Flash video being served by Adobe FlashMedia Server 4.5, the server will translate and send the videoas HTTP Dynamic Streaming or HTTP Live Streaming, bothof which can be played by iOS devices. The mobile version of Internet Explorer 8 for WindowsPhone does not support Flash. The IE9 web browser onMicrosoft Windows Phone 7.5 (Mango) does not supportFlash either.
Other operating systems Adobe Flash Lite is a lightweight version of AdobeFlash Player intended for mobile phones and otherportable electronic devices like Chumby and iRiver. Availability in countries under U.S. economicsanctionsDownloading Flash is blocked in countries that are underU.S. economic sanctions (such as Syria & Sudan). Usersin these countries are blocked (by Adobe) fromdownloading Flash plug-ins for both Internet Explorerand Firefox browsers.
AccessibilityUsing Flash tends to break conventions associated withnormal HTML pages. Selecting text, scrolling, form controland right-clicking act differently than with a regular HTMLwebpage. Many such interface unexpectancies are fixableby the designer. Usability expert Jakob Nielsen publishedan Alertbox in 2000 entitled, Flash: 99% Bad, which listedissues like these. Some problems have been at leastpartially fixed since Nielsens complaints:Text size can be controlled using full page zoom, found inmany modern browsers.
Any Flash player must be able to animate on top of videorenderings, necessitating an intermediate color space conversionbetween video decoding and presentation, that a traditionalmultimedia player would leave for hardware to do at a later stage.This intermediate step splits the hardware acceleration pipeline in two.Depending on the hardware acceleration APIs exposed by theoperating system, doing either part separately in hardware may beunsupported or complicated. For example, on Linux, native Xv videoscaling can not be used because it is made to take video in the formthat comes from the decoder – in YUV color space. However, AdobeFlash Player is able to make use of VDPAU for decoding (provided thatthe computer has an Nvidia GPU), making the Linux version partiallyhardware accelerated. The same challenge arises with native webbrowser video playback, however the implementor may choose adifferent tradeoff between features and performance.Comparisons have shown Adobe Flash Player to perform better onWindows than Mac OS X and Linux with the same hardware. However,the 10.1 update significantly improved performance for Mac OS X.
Flash blocking in web browsers Some websites rely heavily on Flash and become unusablewithout Flash Player, or with Flash blockedFlash content is usually embedded using the object or embed HTMLelement Software that does not support either of these elements, andusers who cannot or will not install a plug-in, will see the replacementtext if this is supplied by the web page. Since Flash can be used to produce content (such asadvertisements) that some users find obnoxious or takes a large amountof bandwidth to download, some web browsers default to not play Flashcontent before the user clicks on it, e.g. Konqueror, K-Meleon. Equivalent"Flash blocker" extensions also exist for many popular browsers: Firefoxhas Flash block and No Script, and Opera versions since 10.5 featurenative Flash blocking. Opera Turbo requires the user to click to play Flashcontent. Internet Explorer has Foxie, which contains a number offeatures, one of them also named Flashblock. WebKit-based browsersunder Mac OS X, such as Apples Safari, have ClickToFlash.
Flash client security Flashs security record[ has caused several security experts to recommend to either not install Flash or to block it. The US-CERT recommends to block Flash using NoScript. Charlie Miller recommended "not to install Flash"at the computer security conference CanSecWest. As of October 31, 2010, The Flash Player has over 100 CVE entries, 65 of which have been ranked with a high severity (leading to arbitrary code execution), and 40 ranked medium. In February 2010, Adobe officially apologizedfor not fixing a known vulnerability for over 1 year. In June 2010 Adobe announced a "critical vulnerability" in recent versions, saying there are reports that this vulnerability is being actively exploited in the wild against both Adobe Flash Player, and Adobe Reader and Acrobat. Later, in October 2010, Adobe announced another critical vulnerability, this time also affecting Android-based mobile devices. Android users have been recommended to disable Flash or make it only on demand. Symantecs Internet Security Threat Report states that a remote code execution in Adobe Reader and Flash Player was the second most attacked vulnerability in 2009. The same report also recommends to employ browser add-ons wherever possible to disable Adobe Flash Player when visiting untrusted sites. McAfee predicted that Adobe software, especially Reader and Flash, would be primary target for attacks in 2010. Adobe applications had become, at least at some point, the most popular client-software targets for attackers during the last quarter of 2009.
Local Shared Objects (“Flash cookies”) Main article: Local shared object Like the HTTP cookie, a flash cookie (also known as a “Local Shared Object”) can be used to save application data. Flash cookies are not shared across domains. An August 2009 study by the Social Science Research Network found that 50% of websites using Flash were also employing flash cookies, yet privacy policies rarely disclosed them, and user controls for privacy preferences were lacking. Most browsers cache and history suppress or delete functions do not affect Flash Players writing Local Shared Objects to its own cache, and the user community is much less aware of the existence and function of Flash cookies than HTTP cookies. Thus, users having deleted HTTP cookies and purged browser history files and caches may believe that they have purged all tracking data from their computers when in fact Flash browsing history remains. Adobes own Flash Website Storage Settings panel, a submenu of Adobes Flash Settings Manager web application, and other editors and toolkits can manage settings for and delete Flash Local Shared Objects. On windows systems, LSOs are stored in the directory: "C:Documents and Settings[currentUser]Application DataMacromediaFlash Player" Deleting the contents of this directory should remove the LSOs (flash cookies) for the current user.
64-bit support 64-bit support of Adobe Flash Player wasreintroduced in version 11, released October 4, 2011.32-bit and 64-bit versions for Windows, Mac and Linuxare released in sync. Other prominent features of therelease include hardware acceleration through theStage3D API.The first experimental release of 64-bit builds of AdobeFlash Player was for the Linux platform, on November11, 2008. The project was closed temporarily on June15, 2010, while Adobe was preparing for the previewrelease on September 15, 2010.