Microsoft had initially pegged support for the Edge browser to only Windows 10, but the move to ditch its own browser engine, replacing it with the Chromium open-source project, has also opened it up for support on older Windows version, including going cross-platform, with promised editions for macOS as well.
The main benefits for the jumping on board the Chromium project, whose rendering engines also powers Google's Chrome, and other several niche browsers, remains the fact that when it reaches the Stable version it will quicken up how the Chromium-based Edge gets security fixes.
The company had last week unveiled the preliminary versions of the browser for Windows 7, 8 and 8.1, which builds for the older Windows versions were marked as the "Canary" channel, with the other more reliable channels, marked as "Dev" and "Beta" to lead the production build, dubbed Stable.
Chromium Edge's Stable build when finally ready will synchronize with Chrome's release cycle, though it's still unclear how Microsoft will deal with providing security updates for the browser. Albeit, there is a likelihood that if Google issues out patches for Chrome, Microsoft Edge will have to be updated as well, because the vulnerabilities will be exploitable on the browser given that they share same engine.
The current reality is that Edge will eventually support the older Windows versions 7, 8 and 8.1, with cross-platform expansions expected later.