I want to install Webmin/Virtualmin to easily control my VPS (I need comfortable tools to create and edit apache vhosts, to setup ssl/https, ftp, mysql…). If I understood correctly, Virtualmin is for virtual hosting management (with many users, hosting accounts, no just one hosting plan), am I right? I want to setup many sites, but all under one server/hosting (like many sites, placed in one typical hosting plan). Do I need Webmin only or I also need to install Virtualmin?
If you want to manage multiple websites, then Virtualmin is more than recommended rather than a naked Webmin.
As you wrote and correctly figured, yeah, you install “it” (be it Webmin or Virtualmin) once on a dedi or a VPS, and from there on it’s the machine’s panel, with which you can manage multiple sites (virtualmin calling them virtual hosts, it’s confusing for new users generally.)
No need to install Webmin first, the Virtualmin installer takes care of everything, you just need a supported Linux OS with minimum server capabilities (lamp) and from there on it’s a single command line in the terminal.