The move won't affect the Windows 10 Long-Term Servicing Channel, which is devices that stay the same over time, such as MRI machines and air traffic control systems. Nor will the retirement affect Server Internet Explorer 11 desktop applications or the MSHTML (Trident) engine. For the most part, though, Internet Explorer will be put out to pasture in a little under 13 months.
Internet Explorer has been part of the Windows fabric for over a quarter of a century. But since the introduction of Edge in 2015, Microsoft has been slowly winding down the old browser. It ended in 2016. Microsoft 365 and other apps will stop supporting IE 11 on August 17th.
Microsoft has urged users who are still clinging onto IE 11 to move to Edge (or another browser, if you prefer) before it ends support next June. Edge has for websites that still need IE. Many organizations still use old apps and sites that don't really work with modern browsers, so that mode will come in useful. Microsoft says it will support Edge's IE mode at least until the end of 2029, giving orgs and IT departments several more years to transition away from those old web apps.