Most likely, your web browser is up to date. Mozilla Firefox and Google Chrome use their own automatic updates, Internet Explorer updates are handled through Microsoft Update, and Linux systems typically use a package manager to keep everything updated. While this is good and will help keep you more secure, more and more exploits seem to target browser plugins - small helper programs that can play movies, music, games, and more right in your browser. This is probably due to the fact that some estimates show 80% of all browsers have some outdated, vulnerable plugins. Adobe's Flash has been in the news a lot recently because Apple refuses to release it on the iPhone or iPad, supposedly due (in part) to security concerns. Adobe routinely patches known bugs and vulnerabilities in Flash, but many times those updates are not installed by users. Google recently started bundling Flash together with Chrome and new updates will be installed silently - the same way Chrome updates itself.
