We recently upgraded to Ubuntu Server 24.04.
This is the operating system, much like windows or Ios, wich serves the basic materials project website. Very widely used in industry supporting about half the websites out there. A little complicated and a bit archaic, with lots of linux commandlines and various configuration, firewall, and all sorts of crazy command line instructions. A bit more complicated and slightly cryptic way of going about things, but its free and open source, built up out of the famous Linux.
This Ubunut Server is the very foundational base layer which everything is built out on top of. SSl certificate, Apache, MySql, PHP , etc is added on top of this ubuntu server foundation to provide the basic materials project website.