system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly is an "infected website"? Can my computer really get a virus for visiting a website?

Never made much sense to me. Shouldn't I actually download & install something to truly get a virus? How would just visiting a website do my computer any harm?
gpt
In a perfect world every bit of software would work perfect and getting a virus from a website would be impossible. 

In the real world perfect security is the thing that is impossible and there is often exploits where something can gain the ability to download things against your will. Some bug in flash or java or whatever that allows a malicious program to get beyond it's intended bounds and alter things on your local system. More rarely but at times even things as simple as jpgs have been able to carry data that overflows some memory and gets code into some other process in your system. 

Any time a flaw like this is discovered it is closed quickly. But there will always be new flaws. There will never be a time when everything is fixed forever and viruses are impossible.