Over the weekend, hundreds of thousands of computers in more than 150 countries were attacked by computer malware.
Malware is computer software, which is used to gain unauthorised access to a computer or computer system.
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This attack seems to have focused more on companies and organisations. But with many of us increasingly living and paying for things online, how can you protect yourself?
We take a look at some of the simple things you can do to stay safe and secure.
Whether you're buying something from a website, or checking your bank balance online, make sure you only use safe and secure websites and WiFi.
Web addresses for safe sites start HTTPS rather than HTTP. They will also display a closed padlock in the address bar.
Never use public WiFi as many of these are unsecured and could leave you vulnerable. Your standard 3G or 4G mobile data is often the best choice.
Stay up to date
Make sure your computer, tablet and smart phone software is up-to-date.
When you get a notification telling you to update software, we often ignore it. But these can be really important and often include updates to close security loopholes.
Make sure you also have active virus protection software on all your devices.
Change your password
Make sure you create a strong password (including capital and lowercase letters, numbers and special characters), don't use the same password on multiple sites and change it regularly.
Never give out personal information. Any legitimate call or message from your bank or an online seller, will never ask you for your PIN number, password or other personal information. If they do, this should be a big red flag.
Avoid online scams
From laptops and tablets to smartphones and fitness trackers, we're constantly connected to the digital world, but this leaves us vulnerable to hackers and scammers.
Fake emails, text messages and websites, which look as if they're from your bank, HM Revenue and Customs or PayPal, are a common tactic.
Thankfully if you know what to look for, you can easily avoid becoming a victim.
What to do if you're a victim
If you notice any unusual or suspect payments from your account, get in touch with your bank immediately.
You should also report any questionable text messages, phone calls and emails so these can be investigated.
You can also contact Action Fraud if you have been the victim of fraud or cyber crime.
This article is provided by the Money Advice Service.