What is windows7.iso?

Answer 1

An ISO file is a CD-ROM or DVD image file. They are used to make backups of optical discs and to distribute discs across the internet. ISOs can be mounted in virtual drives or burned to disc using image burning software. The term ISO is actually the recognised abbreviation for the International Organization for Standardization (this abbreviation was chosen simply because the abbreviations in the recognised languages of English, French and Russian would all be different). CD-ROM uses the ISO 9600 file system, thus all images became known as ISOs, regardless of what format they used.

Windows7.iso is therefore an image of the Microsoft Windows 7 Operating System installation disc.