Legitimate Microsoft Windows 7 owners may download the operating system directly from Microsoft for free. Microsoft requires the entry of a valid product key before allowing the download of Windows 7.
Microsoft supplies digital downloads of Windows 7 in the ISO format, necessitating additional work before the file can be used to install the operating system on a computer. One may opt to burn the ISO file to a blank DVD or alternatively, one may use a USB drive to store the Windows 7 installer files.
It is important to access Windows 7 installation files from a legitimate source or directly from Microsoft. Copies of Windows 7 obtained from unauthorized sources may include undesirable software such as viruses.