system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do sites crash when they get an influx of visitors and what does it take to get the site up and running again?
gpt
A web site is a bit like a shop. 2, maybe 3 people can go through a shop's door at the same time. This is more than enough for most of the time. For some reason, if a crowd of 100 people runs to a shop's door, no one gets in.

The shop owner might chose to lock up till the crowd goes away. He might replace the door with a wider one or he might open a few extra doors to help with the situation if he expects more crowds.