Software that isn’t updated might leave your PC open to infections.Our security software will detect and clean the infections every time they happen, but they will keep happening until you update your software.
This page explains how updates work and where to get them.
If you don't already have Microsoft security software, or you want to reinstall it, see our software download page.
If you're using Windows XP, see our Windows XP end of support page.
For a list of the latest updates see the change log.
Windows will automatically download and install updates once a day for you.
If automatic updates aren't working there might be an issue with your PC: You can also force a download of the latest daily update.
This is the same as when Windows automatically downloads the update, and can be useful if you aren't always connected to the Internet or haven't turned your PC on for a few days.
If you want a more recent update (usually uploaded to this page within the last three hours), you can manually download and install it.
If you want Windows to update your software, go to Windows Update or: Because these updates change once a day, the definition version might be different to what is shown on this page, even after you've clicked the Update button.
Usually, updating once a day gives you a good level of protection, and it prevents us from constantly updating your software and interfering with how you use your PC. This can be helpful if you have hard-to-remove malware, Windows update isn't working properly, or you aren't always connected to the Internet.
If you need to get the latest updates available, you can download and install them from here.