Mac OS 8 was introduced in 1997 as the successor to Mac OS 7 and incorporated over a series of releases the technologies from the failed Copland project as a stepping stone to a future rewritten version of the Mac OS.

OS 8 mostly focused on visual improvements with a new theme (Platinum), but a few underhood improvements were realized as well, including a new multi-threaded Finder (although this was seemingly for PowerPC systems only), while 8.1 introduced the HFS+ filesystem, a native UDF driver for DVDs, and a few other improvements.
OS 8.1 is the last version that will run on an older 68K Macintosh - OS 8.5 and newer required a PowerPC processor.

Mac OS 8 booting up.

The default Mac OS 8 desktop. First thing you will notice is the new 3D-like look on most items. The next thing you will see is the desktop pattern.

Mac OS 8 introduces the new "Platinum" theme with a focus on user customizability and nicer look. It also introduced the ability to set a picture as the desktop background, in addition to a pattern.

The Mac OS 8 about window, now showing a pretty picture of the Earth and a few more details about system memory and such.

Mac OS 8 also has a System Profiler for deeper inspection of hardware and software, and for generating reports about these things.