-by Michael Hardy, Globe correspondent

The National Geographic Society , the 118-year-old research, education, and publishing organization, will announce today that it is joining the online music revolution.

``World Music," National Geographic's major new online venture, will offer thousands of songs from 116 countries and nearly as many genres, from Nordic f olk to Arab c lassical to Senegalese p op. After previewing a song, visitors to the website can purchase it in MP3 format for 99 cents, the same price Apple Computer, Inc. charges at its iTunes Music Store .

National Geographic , a nonprofit organization, will run the website in partnership with Somerville-based Calabash Music , the Public Radio International show ``Afropop Worldwide," the satellite channel LinkTV , and Global Rhythm magazine. The Web address is worldmusic.nationalgeographic.net.

``Obviously, someone who is going to National Geographic for information about a country would be interested in that country's music," said Maure Aronson , the executive director of World Music Inc., a Cambridge nonprofit organization that is not affiliated with National Geographic. `` Once people start listening, they get hooked."

National Geographic's ``World Music" project was conceived by David Beal , a musician and former president of Palm Pictures, an independent entertainment company.

`` The [ National Geographic] website's mission is inspiring people to care about the planet, but it didn't really offer a n audio experience to its visitors," Beal said.

Beal and ``World Music" editor Tom Pryor have worked together on the project since November. The site offers streaming audio and video and extensive editorial content about the world's diverse musical traditions.

``It's a wonderful collaboration for [world music] artists," said Brad Powell, Calabash's president and creative director. Calabash calls itself a ``fair trade" company; it gives a bigger-than-average slice of its revenues to the artist s .

Fifty percent of sales from National Geographic's online store will go to the musician s . The store currently offers about 21,000 songs and 130 music videos. (By comparison, Apple's iTunes store has 3 million songs and 3,000 videos.)

`` This site is still, in many ways, a work in progress," Pryor said.