"System 7" is often used generically to refer to all 7.x versions.
With the release of version 7.6 in 1997, Apple officially renamed the
operating system "Mac OS", a name which had first appeared on System
7.5.1's boot screen. System 7 was developed for Macs that used the Motorola 680x0 line of processors, but was ported to the PowerPC after Apple adopted the new processor.
Soon after the initial release of System 7, the 7.0.1 minor update was
released in October 1991. A patch called "System 7 Tune-Up" also
followed, which fixed the "disappearing files" bug in which the system
would lose files and added "minimum" and "preferred" memory allotments to an application's Get Info box.
In August 1992, the 7.1 update was released which incorporated these
changes and introduced the Fonts folder. This replaced the often
time-consuming method of dragging fonts to and from the System file,
introduced in System 7.0; it also replaced the Font/DA Mover application from System 6, which could also be used with 7.0.