Browser virtualization is the isolation of a Web-browsing application from the operating system (OS) used to access it.
Often, Web-based applications require a specific browser version and plug-in configuration to run. If the browser is updated to a new version, the Web application may no longer work properly. In such a situation, administrators can virtualize the older browser version and the plugins that are necessary to interact with specific applications over the Internet.
In the enterprise, there are two different approaches to browser virtualization that use standard application delivery technologies. Administrators can virtualize a browser as a standalone application, or they can virtualize a whole desktop OS and deliver just its browser to users -- a technique known as application remoting. In either case, administrators can host the applications and desktops either in their own data centers or in the cloud. There are also vendors, such as Spoon and Browsium, that specifically focus on browser virtualization. Spoon's Browser Studio provides a Web portal that subscribers use to virtualize, customize and access their browser applications, which run as if they were local. Browsium's Ion product lets users adjust the current version of Internet Explorer to make it behave like previous versions, which allows legacy applications to remain compatible. Regardless of the specific approach or product used, the virtualized browser runs on the client. The bits can be local, streamed from the data center, or both. But even if the bits are streamed, they still execute locally.
One common -- but unlicensed and unsupported -- example of browser virtualization is with Internet Explorer 6 (IE6). Microsoft no longer supports IE 6 or Windows XP, which is the only operating system that can run IE6. The company also does not support virtualizing IE6 through its own application virtualization tool, App-V, on the grounds that IE6 and Windows XP are inextricably linked. Even though Microsoft says it IE6 can’t be virtualized, organizations that standardized on IE6 and use it to run mission-critical applications can virtualize it in-house, or with tools such as Browser Studio and VMware's ThinApp, but that breaks Microsoft licensing rules. Running IE on Citrix XenApp and XenDesktop, Microsoft Remote Desktop Session Host or VMware View, however, is supported. That's because in such configurations, IE runs in the OS and the application's screen is remoted to users. It’s only when IE is packaged separately from the OS that it becomes a support issue.