Many different character sets exist in the world. Some characters look nearly identical even though they belong to a different character set.
In the domain world, homographs are used to create visually similar domain names to impersonate the website address of an established business. It is nearly impossible for a website visitor to tell the difference between a domain name or email address that contains homographs versus the real thing. Homograph domains are often used for phishing attacks, as attackers can register similar domain names to fool unsuspecting users into thinking they are visiting a legitimate website.