Whats a landline?

So this weekend I get one of those annoying calls from my cable company trying to sell me home phone service to go with my cable/internet. I haven't had a land line phone since early in college and I see no reason to have one these days.
The conversation went like this:

Lady: "May I speak with Marshall"
Me: "This is he"
Lady: "Marshall, I'm from Time Warner and I would like to offer you home phone land line service."
Me: "Landline?...I'm sorry, but I don't seem to understand what that means."
Lady: "Oh, Vonage and AT&T would be wireless and we provide landline service"
Me: "Oh, I didn't think that kind of stuff existed anymore. I use AT&T for my home phone...my cell phone that is."
Lady: "Oh, I assure you that it does still exist. Would you be interested in this type of service for your home?"
Me: "I can't imagine what for, so no."
Lady: "Okay thank you for your time"

Of course I know what a landline is. I just want to try and drive home to the cable company to stop offer that crap to people and get with the times, and I wanted to make it where she gave up trying to sell me anything...its hard to sell when I thought it was extinct.