Sending every request from a single IP is the fastest way to get rate-limited or banned. Rotation spreads requests across many IPs so no one address takes the full load.
How rotation actually works
A rotating setup maintains a pool of proxies and assigns a different one to each request, or to each new session, according to some rule — round robin, random selection, or based on which IPs have cooled down since their last use.
Provider-managed vs self-managed
Some paid providers rotate IPs for you automatically behind a single endpoint, so your code doesn't need any rotation logic at all. With a free proxy list, you build the rotation yourself: pull the list, filter to working proxies, and cycle through them in your own request loop.
What rotation doesn't fix
Rotation reduces the odds of any single IP getting flagged, but it doesn't defeat behavioral detection — if every request from your rotating pool hits the same endpoint in the same pattern at the same speed, sophisticated anti-bot systems can still notice the pattern.