The Zilog Z80 is a CPU designed and manufacted by Zilog.
It its day it was a very popular 8-bit CPU and was at the heart of many computer designs.
The Z80 was compatible with the Intel 8080 in a way which meant that most 8080 code could run unmodified on the Z80. The operating system CP/M was designed to run on 8080 based systems and could also run unmodified on Z80 based systems. Z80 systems were in general more powerful and had more powerful facilities than 8080 systems so this option was popular. Some version of CP/M and many CP/M applications came in more powerful Z80 only versions.
In the 1990s (and beyond) it found a use in the portable video game console Game Boy.