bleepingcomputer[.]com/news/security/domain-shadowing-becoming-more-popular-among-cybercriminals/
DNS servers convert the address you type, e.g., giveawayoftheday[.]com, into the site's actual IP address [xxx.xxx.xxx.xxx], so you wind up with the correct page showing up in your browser. If you look at the address bar at the GOTD game site you'll see game.giveawayoftheday[.]com/, and every site can have these sort of sub domains. And your instinct is to trust it, since after all you're on GOTD's site, right? Well, it turns out that DNS servers can be hacked, and sub-domains added without any notification or signs to the site's owner or anyone else. These illegal *Shadow* domains are terribly hard to detect -- if you're directed to a shadow domain via a link in an email for example, it'll show the address of a reputable site. So be EXTRA CAREFUL.