The top program provides a dynamic real-time view of a running system. It can display system summary information as well as a list of processes or threads currently being managed by the Linux kernel. The types of system summary information shown and the types, order and size of information displayed for processes are all user configurable and that configuration can be made persistent across restarts.
The program provides a limited interactive interface for process manipulation as well as a much more extensive interface for personal configuration--encompassing every aspect of its operation. And while top is referred to throughout this document, you are free to name the program anything you wish. That new name, possibly an alias, will then be reflected on top's display and used when reading and writing a configuration file.
Htop is a free (GPL) ncurses-based process viewer for Linux.
It is similar to top, but allows you to scroll vertically and horizontally, so you can see all the processes running on the system, along with their full command lines.
Tasks related to processes (killing, renicing) can be done without entering their PIDs.
To install htop, enter the command:
$ sudo apt-get install htop