Someone tries to imitate an existing company or person. To do so, they register a domain name that looks so similar to the original that they could be mistaken for each other.
A domain name that looks very similar to the original. The owners' motivation for registering and operating these domain names varies. For example, it could be a case of attempted fraud, where the attackers try to trick the victim into believing they are on the original site. In many cases, such domains are also registered in order to divert website visitors who mistype an address to advertising sites.