In this section, we'll look at listing the packages installed on our systems, and getting the version numbers of those packages.
This will generally be useful if you hear about the latest vulnerability that signals the end of the world, and you are shouted at by your boss to fix it, fix it, fix it.
There are a considerable number of vulnerabilities out there; it just so happens that a few of the bigger ones bleed through to the mainstream media on occasion. These are arguably the most dangerous, as they make people panic, and if there's one thing worse than a bad situation, it's being in a bad situation while everyone around you is losing their heads.
You should also generally keep your systems up to date, because it's a lot more awkward to jump several version releases (when you inevitably do have to upgrade) than to change things...