Cyber security has been a big concern for governments, businesses, and citizens worldwide in recent years. Most people and organizations use antivirus and anti-malware software on their computers and know the signs of phishing scams. However, this hasn’t prevented cyber attacks from occurring.

The latest cyber attack, called WannaCry, attacked more than 150 countries and infected more than 200,000 devices, reports Europe’s law enforcement agency Europol. These enormous numbers make it one of the largest ransomware cyber attacks in history. Here’s a closer look at what you need to know:

What Happened?

The worldwide cyber attack is a piece of malware that locks users out of their devices and encrypts their data unless they pay a $300 to $600 ransom. The attack focused on older versions of Microsoft Windows that had not been updated with the latest security patch. They believe the malware was designed to contact an unregistered domain in its code, and security research found a kill switch by simply registering the domain. However, copycat attacks and variants have already emerged.

What’s Being Done?

For now, tech experts are depending on the kill switch to stop the malware attack. They encourage you to update all of your devices as quickly as possible, but recognize this may take more time for large businesses.

Governments worldwide are preparing for a second wave of attacks, reports The New York Times. For example, Britain’s defense minister told BBC that it’s investing about $64 million in improving cyber security for its National Health Service because it may be using outdated software and was affected by the first attack. Indonesia is taking similar precautions to get its equipment up to date. Governments and tech experts also are looking for the source of the attack by tracking Bitcoin payments and possible leaks of security vulnerabilities from sources like the NSA in the United States.

What Lessons Can be Learned?

The most important lesson you can learn from the WannaCry attack is to keep your devices up to date. You should implement automatic updates for your computer, tablet, and smartphone software. These updates have important security patches and are vital for protecting your information. Microsoft also emphasizes that you should not use pirated software because you will not have access to any updates or patches, making your device more vulnerable to attacks.

A related lesson is to purchase new devices when the older ones are no longer supported by the manufacturer. For example, some of the devices attacked were still running Microsoft Windows XP, which the company doesn’t send automatic updates to. The same thing goes for tablet and smartphone devices.

If you’re still using one of the first generations of the Samsung Galaxy line, for example, you may not be able to receive the latest Android updates. This means you need to buy a new smartphone, like the Samsung Galaxy S8. Not only do these have updated Android software, but newer devices also come with their own security programs, such as Samsung Knox.

If you have been affected by the WannaCry cyberattack, do not pay the ransom. This could encourage similar attacks in the future and it doesn’t guarantee you’ll get all of your information back. CNN has provided a link to an international security project, called nomoreransom.org, to help you unlock your computer without paying the ransom.