system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why after downloading some applications, do I need to restart but others work straight away?

^
gpt
Because some applications use low-level resources which are already loaded into memory and used continuously by other applications and the operating system as well. Since reloading that particular resource in to memory is way too hard without crashing other applications or the OS itself, the best is to make the user reload the full operating system, hence the need to restart.