What are packages in Linux and most importantly, where does the OS get them from (From the Internet, already in the installed system, etc.)?

Question

linux

For example, if you write apt-get install chrome in the terminal, google chrome will be installed, but where does the OS download these files from? If she downloads them from the Internet, then from the official site or from some of her own? And can the OS in a similar way, accidentally install malware through the terminal? In general, the process itself is interesting.
PS I apologize for the stupid question, I'm just a goof in linuxe xD

Answer 1

https://ru.wikipedia.org/wiki/Repository
https://ru.wikipedia.org/wiki/Control_system...