Htop is an open source program that provides users with an interactive and sophisticated process viewer and manager for any Linux-based operating system. It has been designed from the ground up as a drop-in replacement for the standard Top utility found on almost all distributions.
It is a command-line software that runs on both the Linux console and X11 terminal emulator applications, and requires the ncurses library for displaying its interactive menus and CLI interface.
Theoretically, the application offers almost the same functionality as the default top program. The main difference is its looks and handling or certains tasks. It also comes with a different set of keyboard shortcuts.
Its user interface is divided into two main sections, a basic system monitoring and information one, and the process viewer, which occupies the biggest part of the screen. In addition, it displays a menu on the bottom edge of the screen, which uses the F keys.
While the process viewer part of the application is similar in functionality with the one provided by top, the system monitoring component is quite different, as it displays a really nice, real-time graphic visualization of live CPU, RAM and SWAP usage.
When running the application in an X11 terminal emulator, it will automatically change its appearance depending on how the user resizes the window. For example, you can view more information if the window is bigger or fewer if it’s smaller.
Another interesting feature is the ability to interact with the program using a mouse device, only when using it in any X11 terminal emulator application. For example, you can select a single process in the viewer, which will remain highlighted until it is closed or the app is terminated, and give it signals.
In conclusion, Htop is a very handy replacement for the old-school top task manager, specifically designed for the modern Linux/UNIX system administrator.