The biggest ransomware attacks: How has ransomware affected businesses around the world?
Ransomware is a type of malicious software that will block access to your network and threaten to delete your files unless you pay a ransom.
The most common, and destructive type of ransomware is 'Locky', which comes in the form of a document that requires the recipient enables macros. Once this is done, a download will begin and when complete it will scramble your data and demand payment for it to be released. Most payments will be demanded in Bitcoin as it's less traceable.
However, this month WannaCry ransomware has been thrust into the headlines after it infected hundreds of businesses across the globe, including 47 Trusts within NHS England.
A ransomware attack isn't necessarily a very costly operation, with most hackers demanding around $600 (£465) to release files, but they can highlight the vulnerabilities within organisations, depicting a lack of funding, security procedures and infrastructure in place.
We look at some of the most damaging ransomware attacks in history...