Using a computer would be imposible without software. We need software just for the operating systems to function, because the OS is software too. When we buy a personal computer, it's generally for browsing the Internet (using software we call a "browser"), checking email (software), and or playing games (... software.)
Running servers remotely isn't any different. We build them to run software for us. The only difference in a business setting is you're likely going to be running software that was developed at the organisation, as well as software developed by others, whether it's free, open-source or commericial.
On Ubuntu (and Debian, another Linux distribution), you use the
apt command to manage packages. The
apt command has several sub-commands that we'll look at. We're going to install some utilities and software on our system using