What does security software even mean now? It’s such a vast concept that it can cover everything from file scanning to parental controls and everything in between. It pretty much covers everything except someone telling us, "Don’t do that, you’re going to regret it!"
It is the most quickly evolving type of software that we run on our computers, but it hardly gets noticed.
But that’s the purpose of security software: to do its job in the background and to never ask us for anything. It keeps its mouth shut, and we don't end up with a hijacked system.