By no longer charging for its key asset - the information - Britannica has fundamentally shifted the focus of its business.

It intends to make money through advertising and e-commerce. For example, someone looking up the Battle of Waterloo on the website could be offered military models or war games.

'A bold step'

Britannica spokesman James Strachan said: "This is a bold step and one that we did not take lightly. It is a historic day - by putting the Encyclopaedia Britannica online we can reach 200 million people.

"We have looked into this and feel that, even though we are supplying a substantial amount of content for free, we have a secure business plan for the future."

Web users around the world will be able to browse through 44 million words, kept up to date by 7,000 researchers around the world. Since the first edition in 1768, the encyclopaedia has expanded to 33,000 pages and costs £800.

The site will also carry news services, magazine articles and collect information and links to other parts of the internet.

Users who do not want to view the advertisements can access a 'pure' version of the encyclopaedia. This is free for 30 days and then costs five US dollars a month.

Mobile access

The new site is aimed at US users but a similar site for UK net surfers is planned for early next year.

Mr Strachan said: "We have 230 years of editorial experience and we feel that the internet provides us with the best possibility yet of reaching the most people.

"Now that mobile phones can get access to the internet, the pub quiz will never be the same again."

Colleague Don Yannias added: "Purchasing Encyclopaedia Britannica was once a major milestone in a family's life, but today we are fulfilling our promise to make it more accessible to more people worldwide."

The company launched its first website five years ago. It will continue to publish its CD and DVD versions, but bibliophiles can look forward to a new 40 volume paper edition of Britannica in 2001.

Britannica facts

• The first volume of the Encyclopaedia Britannica began printing in December 1768, in 100 fortnightly parts.
• The original volume was priced at sixpence per instalment.
• Famous contributors have included Robert Louis Stevenson, Leon Trotsky, Marie Curie, Sigmund Freud and Professor Stephen Hawking.
• The current set of volumes weighs nine stone and stands 120 cm (four feet) long.
• The website will carry modern cultural topics, such as features on rock music of the late 1960s.