tl;dr: A deep dive into what every field in htop/top actually means on Linux, covering uptime, load average (an exponentially damped moving average that includes uninterruptible processes, not just CPU usage), PIDs, process states (R/S/D/Z/T/t), niceness/priority, and the various memory metrics (VIRT/RES/SHR/MEM%). The author also walks through each default process running on a fresh Ubuntu Server 16.04 install, explaining what it does and whether it can be safely removed, using tools like strace, /proc, and ps to demonstrate where the data comes from.