atop is a full-screen performance monitoring tool that provides detailed reports about all system processes, including those that have already terminated. It does this by continuously logging system activity at regular intervals, storing that information for later use.
These logs can be used for various purposes such as system analysis, performance tuning, identifying bottlenecks, debugging issues, or tracing the cause of an unexpected overload.
Unlike traditional tools like top or htop, which only show live system data, atop gives you the ability to look back in time and inspect exactly what was happening during any logged interval, which makes it especially valuable for system administrators for keeping servers running smoothly.