SAN FRANCISCO?Microsoft plans to close its Encarta online encyclopedia, which competes in an arena dominated by communally-crafted free Internet reference source Wikipedia.

The US software colossus said that on October 31 it will turn off all its Encarta websites everywhere except in Japan, with that service to be terminated on the last day of December.

"The category of traditional encyclopedias and reference material has changed," Microsoft said in an online message at its Encarta website on Monday.

"People today seek and consume information in considerably different ways than in years past."

Encarta was launched in 1993 as competition for traditional reference books such as those offered by Encyclopedia Britannica.

Encarta was originally available for purchase as a multimedia computer resource in DVD-ROM or CD-ROM formats and eventually became available online on a subscription basis.

Encarta's popularity faded after the nonprofit Wikimedia Foundation launched Wikipedia online in 2001.

While Wikipedia lets users continually update or refine entries, improvements suggested to Encarta must pass muster with editors before eventually being incorporated into the data base.