Apple and Microsoft take very different approaches to OS development, and one key feature is missed by anyone moving from macOS to Windows. Apple's Quick Look previews file contents inside the Finder, simply by pressing space with the mouse pointer hovering over a file. There are several Windows add-ons that bring Quick Look to Explorer, but the easiest to use is also free and regularly updated. With a long list of supported file types, it lets you preview files quickly, without having to give screen real estate to Explorer's Preview pane or waiting for apps to launch. QuickLook is unobtrusive, and fast, and you can get it from GitHub or from the Store.