You can find the link to the DEB package of HTOP at the bottom of this page on the Debian website. Theoretically you can download the HTOP DEB package yourself and install it manually. In this case APT downloads the HTOP DEB package for your PC’s architecture, from the Debian software repository, and installs it on your system. An example for installing the HTOP interactive processes viewer: So whenever you install software with APT, under the hood it installs the software from the DEB package. All software that these Linux distributions support and maintain are essentially DEB packages. If you used either Debian or Ubuntu before, you undoubtedly worked with DEB packages already.

Since the Ubuntu Linux distribution derives from Debian, it supports DEB packages for software installations as well.

What actually is a DEB package? A DEB package is a file format that specifies how to bundle and install software on the Debian Linux distribution. Since Ubuntu derives from Debian, the explanation applies to Ubuntu based systems as well. This article explains how you can manually install software bundled as a DEB package onto your Debian system. Luckily, a lot of third party software providers make a DEB package available for you to install. Sometimes you want to install software that is not readily available in the Debian or Ubuntu online software repository.

Debian show installed packages