The Swiss Institute of Technology, Google and IBM conducted the study 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.
It's like installing a burglar alarm, but leaving the front door wide open, and not switching it on.
Each browser has different ways of installing new updates.
Firefox just does it itself and is just about painless to do. Every now and then a upgrade will come along and one of your add-ons stops working, until the author does a patch, but thats least of your worries.
Internet Explorer's patches and updates are downloaded via Windows Update. If you don't know what windows update is and your using a windows pc, you really going to be in trouble, as Microsoft are forever fixing little holes here and there.
Some users have been unable to install the latest version of Internet Explorer due to them having hacked copies of windows XP. If thats the case, I'd switch to firefox
If anyone wants any questions answering about keeping your pc up-to-date, post below.