Windows 10 Media Creation Tool is a portable program which provides various ways to update a PC to Windows 10 build 2004 or, if you're an existing Windows 10 user, get hold of the very latest version (May 2020 Update).
You can use the package to install Windows 10 on the current PC, if it's running Windows 7 or 8.1, or reinstall Windows 10 on a system where you've already activated Windows 10.
There are also options to create a bootable environment (a USB key or ISO file) for installing Windows 10 on another PC.
The good news is, if you use the Windows 10 Media Creation Tool to move up from Windows 7 or 8, you get to keep all your installed software, data, files and other settings. Just the operating system is updated.
Please note, there are several points to remember when using the Windows 10 Media Creation Tool.
It won't work on Windows XP or Vista PCs, even though these can be upgraded to Windows 10 using a fresh install. You'll need to either download the Windows 10 ISO and create your own USB or install DVD or ask a friend with a Windows 7 or 8 machine to use the Tool for you to create a bootable USB stick or DVD.
If you choose to build an installer on a USB key, any existing data it contains will be overwritten. Ideally you'll need a blank formatted USB stick before starting and we'd recommend using an 8GB stick as Windows 10 is over 5GB.
If you choose to build a bootable install DVD, due to the size of Windows 10 (over 5GB), you'll need a blank dual layer DVD. Make sure your drive can burn a dual layer disc.
If you've not installed Windows 10 before, you'll need a product key. You can install Windows 10 as a very limited trial, but you'll be expected to activate within 48 hours after install (don't worry, Windows 10 will prompt and remind you). You don't need to have your product key to hand during installation.
Microsoft also warns that "if you have Office 2010 or earlier and choose to perform a clean install of Windows 10, you will need to locate your Office product key". This may also apply to security software. In some instances, you'll need to re-install security software if you move up to Windows 10 from Windows 7 or 8.
There are more instructions on the Media Creation Tool page, if you need them.
A handy way to build your own Windows 10 installer.