System Monitors/Task Managers
System Monitors are used to display information about what your computer is doing. Commonly data points are CPU usage, CPU frequency, CPU temperature, RAM usage, disk usage and network usage, as well as breakdowns per process.
htop
htop is a terminal process/system monitor, including I/O monitoring. htop can also manage processes.
Btop++
Btop++ is a rewrite of bpytop in C++.
Neofetch
Nethogs
Nethogs is a terminal network monitor that displays network usage per process.
Intel GPU Top
Intel GPU Top is a terminal GPU monitor for Intel GPUs.
NCurses Disk Usage (ncdu)
NCurses Disk Usage (ncdu)