ICANN has started to accept applications for new generic top level domains, which will include words for brands, and non-Latin characters.
The organisation said that the move "could trigger a dramatic expansion of the internet" in a statement on Wednesday to mark Thursday's launch.
"Starting today, ICANN begins accepting applications for new generic top-level domains (gTLDs)," said the statement. "The world of .com, .gov, .org and 19 other gTLDs will soon be expanded to include all types of words in many different languages."
ICANN has faced a number of criticisms of the application process, including that the fee, at $185,000 (£120,000), may be too high for applicants from smaller organisations, charities, and developing countries.
The organisation said it had changed its applicant support programme to offer "limited financial assistance" to qualifying applicants. ICANN has provided a $2m seed fund for the programme.
"Through this programme, applicants, especially from developing economies, have access to financial assistance in the form of an evaluation fee reduction and other in-kind or community pro bono services," said ICANN. "The financial assistance element of the program will allow a limited number of qualifying applicants to pay a US $47,000 evaluation fee instead of the full USD $185,000."
The programme has been altered to make refunds more available, and to make certain trademark owners eligible for fee reduction, said ICANN. The organisation now has a TLD online application system for new registrants.
Some organisations have called ICANN's ability to provide efficient internet governance of thousands of new TLDs into doubt. A coalition of organisations involved in a long-running dispute over the .jobs domain accused ICANN of "inaction" in a letter (PDF) published on the dot-nxt news website on Wednesday.