Rules - are a set of conditions by which you can take a proxy from the list of "live" proxies. Thus, the rules are applied to those proxies that have already been checked. Rules can be used to customize the outputting of proxies according to various criteria. For example, you only need anonymous proxies or elite ones, with maximum speed and minimum latency, unbanned on Google and Twitter, only Russian proxies to work with Russian social networks, etc. Read more about setting up rules here.