The takeover will top the bewildering series of acquisitions and mergers taking place this year on the portal front, with companies building brands and adding features to retain Web users by acting as one-stop shops.

With Sun Microsystems also in on the deal, Microsoft's MSN portal, its Explorer browser and its NT operating system and server software will face a unified challenge of equal weight.

How the stats stack up

America Online this month announced that worldwide membership of its online service had exceeded 14 million. More than a billion e-mails were sent over AOL in October and there were 21 million visitors to its AOL.com Website, according to Relevant Knowledge.

Netscape's Netcenter portal drew nearly 16 million visitors in October, while Microsoft.com had 20 million and its msn.com portal, 12 million. Yahoo! is the most visited Website with 25 million visitors.

Netcenter might well be maintained following the takeover. It serves a different audience - mainly office workers - compared to the home users who have helped AOL to market dominance.

The CompuServe online service has managed to keep its identity since it was taken over by AOL, as it too has traditionally catered for a professional audience.

Browser battle could take decisive turn

When AOL buys Netscape, it could replace the Microsoft Explorer browser, which underlies its Internet access software, with Netscape's Navigator.

In the latest survey by the International Data Corporation, Explorer edged ahead of Navigator for the first time in the battle for market share.

It had 43.8% compared to Netscape's 41.5%, but 16 percentage points came from AOL's uptake of the browser. Its deal with Microsoft to include its browser with its software runs out at the end of the year.