America Online Inc. has officially launched its ad-supported portal out of beta, the latest step in AOL's ongoing shift from a subscription-only service to one challenging Yahoo Inc., Microsoft Corp.'s MSN and Google Inc. in the multi-billion-dollar online-advertising market.

The end of beta testing for AOL.com was announced quietly this week on the Dulles, Va., company's site for beta testers.

"AOL.com is no longer in Beta! Thanks very much for all your testing assistance," the company said in a posting.

AOL, a unit of Time Warner Inc., has been rolling out features on the beta version for months. Besides search, email and other services found on competing portals, AOL is especially focused on video entertainment, which is geared toward broadband users.

The portal includes a video homepage that acts as a hub for the network's multimedia content, including music videos, news, sports and entertainment.

"Video is the lead play for us in terms of how we will draw new visitors to the portal," David Liu, general manager of AOL.com, told TechWeb in a previous interview.

Rival Yahoo has built its business around entertainment for years, and is also heavily into video. MSN has also made multimedia content its focus. In online advertising connected to search results, however, search giant Google has raked in the most revenue, so far.

AOL's biggest potential advantage over rivals is in unique content, according to some experts. The portal, for example, develops its own music videos through its online service Music Sessions and Music Live, and it's parent company Time Warner could work with its subsidiary one day to develop more original content.