In January of this year, Microsoft formally introduced the new Edge browser based on the Chromium engine. It introduced a bunch of new features compared to the previous UWP-based version, now known as Edge Legacy, such as support for Chrome extensions, profiles, and more. Naturally, the new version of Edge is set to eventually replace Edge Legacy, and Microsoft has said that Windows 10 version 20H2 will ship with the new browser for the first time.
Today, Microsoft announced that it's preparing to drop support for Edge Legacy, meaning it will no longer receive security updates. This will happen on March 9, 2021, at which point most Windows 10 users should already have the new Edge, since the browser is being pushed through Windows Update.
Microsoft also announced that many of its web-based services, such as Office on the web and Teams, will stop supporting Internet Explorer 11. In fact, Teams will stop supporting IE11 as early as November 30, which means you may be unable to use the service altogether, or experience some kind of problem with it. The rest of Microsoft 365 will stop supporting the browser a full year from today, on August 17, 2021.
One of the big new features of the new Edge is IE Mode, which is meant to ensure complete compatibility with legacy apps and websites that require IE11. This essentially means that IE11 apps will be housed in a tab inside Edge, acting like a regular website, thus removing the need to use a modern browser and IE11 at the same time. This is an enterprise-only feature, though.