NEW YORK — The Internet’s key oversight agency relaxed rules last week to permit the introduction of hundreds, perhaps thousands, of new Internet domain names to join “.com,” making the first sweeping changes in the network’s 25-year-old addressing system.

The Internet Corporation for Assigned Names and Numbers unanimously approved the new guidelines on the final day of weeklong meetings in Paris. ICANN also voted unanimously to open public comment on a separate proposal to permit addresses entirely in non-English languages for the first time.

New names likely won’t start appearing until at least next year, and ICANN won’t decide on specific ones yet. The organization still must work out many details, including fees for obtaining new names, expected to exceed $100,000 apiece to help ICANN cover up to $20 million in costs.

Domain names help computers find Web sites and route e-mail. Adding new suffixes can make it easier for Web sites to promote easy-to-remember names — given that many of the best ones have been claimed already under “.com.” New names could cover locations such as “.nyc” and “.berlin” or industries such as “.bank.”

The new guidelines would make it easier for companies and groups to propose new suffixes. ICANN had accepted bids in 2000 and 2004, but reviews took much time, and one — “.post” for postal services — remains pending more than four years later. Ultimately, only 13 have been approved in those two rounds.