In 1998, the United States government led the creation of the Internet Corporation for Assigned Names and Numbers, a nonprofit that oversees domain names. ICANN describes itself as a global “bottom-up community” that does not regulate prices or police online content.

A relatively small number of well-known domain names, including .com and .org, go back to the 1980s. When ICANN was created, it began overseeing these legacy names and country and territory domains like “.ca” for Canada, “.de” for Germany and, of course, “.ai” for Anguilla.

As the internet grew, ICANN created more digital real estate, broadening the domain-name market. Roughly 1,200 new top-level domain names — the letters that appear to the right of the dot — approved by ICANN have begun operating in recent years.

There is no way to track precisely how domain names are used, but experts estimate that as few as half are the addresses for websites or email. Big companies buy up thousands of addresses to cover variations of their corporate or brand names, to prevent illicit operators from using them. And speculators own the rights to many millions of other names, hoping to resell them for big payouts.

The resale prices range from a few dollars to millions. Last year, voice.com sold for $30 million to Block.one, a start-up building a social media network called Voice.

Serkan Piantino, a former director of A.I. research at Facebook, considered buying a .com address when he founded his start-up, Spell, in 2017. But he opted for spell.run instead.

Spell’s software tools help developers create products with machine learning technology. And “spell run” is the command users type to move their code into Spell’s cloud software.