This is htop, an interactive process viewer for Linux.

Comparison between 'htop' and 'top':
- In 'htop' you can scroll the list vertically and horizontally to see all processes and full command lines.
- In 'top' you are subject to a delay for each unassigned key you press(especially annoying when multi-key escape sequences are triggered by accident).
- 'htop' starts faster ('top' seems to collect data for a while before displaying anything).
- In 'htop' you don't need to type the process number to kill a process, in 'top' you do.
- In 'htop' you don't need to type the process number or the priority value to renice a process, in 'top' you do.
- In 'htop' you can kill multiple processes at once.
- 'top' is older, hence, more tested.