Veracrypt lets you create an encrypted VHD. An optionally encrypted Zip or 7-zip file can be renamed and stored anywhere. The main user alternative is to hide stuff in plain sight. Intelligence agencies & cybercriminals are working on tools that alter the BIOS, or reportedly in the NSA, alters the hard drive firmware, so that files & folders can remain invisible as long as that device is used, not being limited to just that copy of Windows.

WinPE or another copy of Windows or Linux. It can be done with a driver that loads with Windows, but those Invisible files & folders will be visible when that driver's not loaded, e.g. A so-called root kit, &/or apps like Protected Folder Pro, can tell the OS to not see something, again for practical purposes making it invisible. The NSA reportedly developed their own file system, that no one else has the ability to work with, just for that - a partition using that file system is for practical purposes invisible because no software understands it to see it. When it comes to hiding files &/or folders, that's something that the file system, e.g. BitDefender, prevents many apps from accessing protected folders, so you don't have to worry if they're locked or unlocked, the potential weakness being if ransomware somehow tricks the security software into thinking it's allowed access. The catch is that if ransomware tries to do its thing while you've got those files unlocked to work with them, they're not going to be protected. IObit is correct when they say that preventing access to files, in this case by using Protected Folder Pro, means that ransomware cannot encrypt those files & delete the originals.

Protected folder license code