Sucuri SiteCheck website security monitor is used to monitor websites for malware, blacklist status and other security issues and Sucuri CloudProxy Firewall safeguards sites and those who visit them from attacks of all kinds.
nginx [engine x] is a HTTP server and mail proxy server written by Igor Sysoev.
Content Security Policy is best used as defense-in-depth, to reduce the harm caused by content injection attacks.
Sites who has this tag are verfied by google to use WebMaster tools