A brief history of Internet Explorer

At the turn of the 21st century, Internet Explorer ruled the web. Then, for a few years too many, Microsoft put Internet Explorer development on autopilot. That left a giant competitive opening, and over the past dozen years, alternative web browsers and development tools, some of them quite good, emerged. For many developers, especially those working on non-Windows platforms, Internet Explorer became a pesky item on a compatibility checklist rather than a serious development target.

Microsoft has been positively sprinting in recent years to catch up to the competition in terms of performance and standards compliance and to win back developers. Internet Explorer 11—which is available for Windows 7, Windows 8.1, and Windows 10—is an excellent competitor. It’s fast and generally compliant with web standards.

The trouble is that most enterprise deployments of Windows haven’t taken advantage of the speed and standards compliance of the latest Internet Explorer release but are instead stuck on an old version, one that’s slow and increasingly unable to keep up with the modern web. The reason is most often compatibility with legacy web apps that typically require Internet Explorer 8 to work properly.
The problem is exacerbated by the fast-paced development cycles of competing browsers, including Google Chrome and Mozilla Firefox, which in recent years have pushed out automatic updates for their Windows browsers far more frequently than Internet Explorer.

In general, that fast update cycle means anyone using Chrome or Firefox has quicker access to features based on the latest web standards. Meanwhile, Microsoft’s overly generous support life cycle has allowed older versions of Internet Explorer to remain in use years longer than is sensible on the fast-changing modern web.

As of January 12, 2016, that all came to an end. On that date, Microsoft changed its support life cycle for Internet Explorer. Under the new policy, only the most recent version of Internet Explorer available for a supported operating system will receive technical support and security updates.
For the first time, only one version of Internet Explorer, Internet Explorer 11, is officially supported on PCs running Windows 7, Windows 8.1, and Windows 10. A feature called Enterprise Mode for Internet Explorer 11, which I discuss later in this chapter, is designed to address compatibility issues in the enterprise.

But Internet Explorer isn’t the default web browser for new PCs running Windows 10. That honor goes to the new Microsoft Edge. Enterprises can still choose to make Internet Explorer their default browser across all supported Windows versions, but otherwise Internet Explorer will be relegated to a compatibility role.

Source of Information : Microsoft Introducing Windows 10 For IT Professionals