Hi i am new to this website i wanna try to download one of the old windows versions but im worried downloading it will change my entire operating system will it do that?
No. Just downloading it will not change anything on your computer. You will need to install it. But most, if not all, of the old Windows versions on this site won't run directly on modern hardware. To run them, you'll need virtualization software. VirtualBox is probably the easiest to get started with. It's free and there are a ton of guides out there.
I generally prefer VMware workstation myself, but it's not free.
Also, note that the files you download from this site are usually 7z files. You'll need to extract them with 7zip. Inside is usually an ISO file or IMG file which is a bit for bit copy of the original installation media. You can mount this in the virtualization software you're using, or burn it to a CD or disk and boot up an old computer with it to begin the installation process.
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I generally prefer VMware workstation myself, but it's not free.
Also, note that the files you download from this site are usually 7z files. You'll need to extract them with 7zip. Inside is usually an ISO file or IMG file which is a bit for bit copy of the original installation media. You can mount this in the virtualization software you're using, or burn it to a CD or disk and boot up an old computer with it to begin the installation process.