Keeping your system patched up and protected

Computers aren't perfect. In fact, they're really stupid and will do exactly what you tell them. If you tell them to make a pizza, they'd do it if they had arms and legs. But, if you tell them to wipe a hard drive, they'll do it. If you tell it to turn off, it'll do it. If you give it some really complicated instructions where you confuse the computer so bad that you've made it through its security checks and can now run whatever code you want, that's an exploit. That's why you need to update your system with the latest security updates and keep it protected against viruses when necessary.