*.in-addr.arpa domains: lot of requests in my OpenDNS account. I know this should be normal and it's about reverse DNS. I've been reading here and there but still I can't really get how it works and why I get so much requests (higher number than www.google.com). I'd just need someone that, like Einstein suggested, could explain to me what this reverse dns is used for like he would explain it to his grandmother :)

Thanks a lot!