Can the world live without Wikipedia for a day? The shutdown of one of the internet's most-visited sites is not sitting well with some of its volunteer editors, who say the protest of anti-piracy legislation could threaten the credibility of their work.

"My main concern is that it puts the organisation in the role of advocacy, and that's a slippery slope," said editor Robert Lawton, a Michigan computer consultant who would prefer that the encyclopedia stick to being a neutral repository of knowledge. "Before we know it, we're blacked out because we want to save the whales."

Look it up ... this is what you'll see on the Wikipedia page.

Wikipedia will shut down access to its English-language site for 24 hours beginning 4pm AEDT today. Instead of encyclopedia articles, visitors will see information about the two congressional bills and details about how to reach legislators.

It is the first time the English site has been blacked out. Wikipedia's Italian site came down once briefly in protest to an internet censorship bill put forward by the Berlusconi government. The bill did not advance.