The fixes prompted urgent action by government services and other organisations.

The fixes caused government services and other organisations to act quickly.

They also advised organisations that could not update in time to consider taking affected sites offline.

Here, offline means that the websites would not be available to people using the internet.

The Netherlands’ cyber-security agency said it was taking its own website offline because of the flaws.

The agency was making its website unavailable on the internet.

Finland shut down its public web services, and the Dutch agency said it was taking its website offline because of the flaws.

The agency was making its website unavailable on the internet.

Organisations may need to weigh the risk of staying online against the disruption of taking a site offline.

Taking a site offline means making it unavailable on the internet.

Here, cyber-security agencies urged them to apply the fixes, or consider taking affected systems offline if they could not update in time.

Taking affected systems offline means stopping people from accessing them over the internet.

The Edinburgh council website and several BBC programme sites were inaccessible, but no link to the PHP flaws had been confirmed.

The websites could not be reached or used by visitors.

The Edinburgh council website and several BBC programme sites were inaccessible, but no link to the PHP flaws had been confirmed.

No one had shown or established that the PHP flaws caused the website problems.

CERT-EU, the European Union’s cyber-security service, said the flaws could affect versions going back to PHP 5, which launched in 2004.

This means that versions from PHP 5 onward, including newer ones, could be affected.

Users of PHP 8.1 or older were urged to upgrade.

They were urged to change to a newer version of PHP.

The vulnerabilities have been called especially severe.

Here, severe means very serious.

The cyber-security firm Wiz described the flaws as the most severe it had ever found using artificial intelligence.

Here, severe means very serious or dangerous.

Wiz also estimated that about 70 percent of the internet could be affected.

Wiz calculated or judged that the number was about 70 percent, rather than giving an exact count.

What is the main lesson for organisations that rely on website software like this?

Organisations that rely on this software need it to work for their websites.

Organisations may need to weigh the risk of staying online against the disruption of taking a site offline.

This means carefully comparing the danger of staying online with the problems caused by taking a site offline.