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I'm using Windows 7 64 bit and have two versions of IE9 (32 and 64 bit) on my machine. Why are there two versions of IE9 on my machine? As far as I know, other browsers do not have two versions.

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migrated from Aug 8 '11 at 19:07

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I believe that the 64-bit version is more about being forward-looking and compatible with webpages that might have high RAM usage. Some people like to use 64-bit browsers for various reasons, though it isn't the mainstream. However, most of the browser plugins are 32-bit, and so the 32-bit browser is provided as the default for compatibility with most websites.

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"high RAM usage` - the day a website can take up over 2GB RAM and not be trying to use some esoteric exploit will be a strange day indeed – Phoshi Aug 8 '11 at 19:42
@Phoshi I would expect that the high RAM usage would be due to some video plugins or Flash, or perhaps it's loading a lot of high-resolution images, or the javascript needs 64 bits of precision for a special use case. But since Flash is typically 32-bit, it might not be a realistic thing to expect right now, true. However, there is a niche group that uses 64-bit browsers. Most of us only care about the 32-bit one. – Ben Richards Aug 8 '11 at 20:08
Indeed, it's unlikely to happen today, but it probably will one day. I wonder when! – Phoshi Aug 8 '11 at 21:09
Haha. Plugins and Flash? Have fun downloading 2GB graphics. . . – surfasb Aug 8 '11 at 22:06

Both versions exist because there are many third-party extensions and plugins that are not yet 64-bit compatible. If you need to use one of these plugins and you are running the browser in 64-bit mode, the plugin will either fail to work altogether with no error message displayed, or you will get an error message from the third-party plugin instructing you to quit IE in 64-bit mode, launch it in 32-bit mode instead, and reload the page that requires the plugin.

At this point it is practical simply to run IE in 32-bit mode all the time, even if you are running Windows Vista 64-bit or Windows 7 64-bit.

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Since Windows supports 2 versions (32-bit & 64-bit), so it has provided two compatible corresponding versions of IE9.

Two versions of Windows is provided because the 64-bit version of Windows handles large amounts of Random Access Memory (RAM) more effectively than a 32-bit system. The terms 32-bit and 64-bit refer to the way a Computer's Processor (also called a CPU), handles information.

Also I would like to let you know that if the IE9 program / software is specifically designed for the 64-bit version of Windows, it won't work on the 32-bit version of Windows. (However, most programs designed for the 32-bit version of Windows do work on the 64-bit version of Windows.)

Hope it helps.

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sorry i forgot to indicate that both browsers are on my machine. that is my confusion. – meddle Aug 8 '11 at 17:26

The 32-bit version is for the 32-bit version of Windows.

The 64-bit version is for the 64-bit version of Windows.

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I have both versions on my machine that runs Windows 7 – meddle Aug 8 '11 at 17:20
You can run the 32-bit version on your 64-bit machine, but not the other way around. – bigmattyh Aug 8 '11 at 17:35

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