To enable the classic old legacy Search Box in Explorer on Windows 10, you can tweak the Registry or use Mach2. Do it if you do not like current default behavior.

The File Explorer changed its name in Windows 8 (it was previously known as the Windows Explorer), but it's gotten more functionality in Windows 10. Because the File Explorer is where you'll go to ...

You may need to search in a Windows 10 computer to find files, folders, or programs. Windows 10's search feature is a quick way to find what you need.