A new study says that almost half of the UK population is at risk because we are slack at updating our computer security.
The research was carried out by the Swiss Institute of Technology, Google and IBM and found 600 million users had not updated their browsers.
"Failure to apply patches promptly or missing them entirely is a recipe for disaster", the report said.
And it added that cyber criminals are taking advantage of this to use websites to attack unsuspecting web users.
The team have now put forward proposals including putting a "best before" date on browsers, so that internet users know when they need to update their software to protect against phishing attacks, viruses and other cyber crime.
This is hoped will remind users to download the patches that software providers send out.
The study found that it is Firefox users who are best at finding up-to-date versions of their browser, while Internet Explorer users are the slowest to update.
More than 83% of Firefox users were using the latest, most secure browser version, compared to 65% of Safari users, 56% of Opera users and 47% of Internet Explorer users.