nmon is a popular monitoring tool that was originally built by IBM engineer Nigel Griffiths in the 1990s to monitor operating system performance data for AIX. Despite its original success, the tool underwent significant changes over the years, with Griffiths revisiting and revamping it multiple times. In 2018, Griffiths re-built nmon from the ground up to bring it into alignment with modern computer systems, focusing on four key areas: file format, metrics collection, data storage, and data visualization. The updated tool now uses standard JSON and InfluxDB line protocol for data exchange, collects virtually every possible system performance stat, and utilizes Grafana for real-time data visualization. With these changes, nmon has become much more powerful and useful in modern technology stacks.