I'm not one that enjoys or is part of the "flaming" culture that seems to be quite popular here, but ... I do agree with you, it is a silly question lol!
Certain software use multithreading technology, such as ScrapeBox, which using several different connections at the same time - which means, for example, it's like using Google to perform
10 Searches every second.
Google will know you're performing 10 searches per second because they're all coming from the same IP Address - so to make it look like they're individual normal searches, you use a list of proxies.
The above is just an example. But the basic principle of a proxy is to hide your identity online when wanting to do
multiple tasks. Plus, resetting your router, although changes your IP Address, still results in the same IP Series... so it isn't as effective.
Hope that helps!