When I first heard of tabbed browsing, I couldn't understand the point. I wondered why people made such a fuss when Apple released Safari without it. Then I tried it, and now I can't live without it.
But I struggle to explain the concept. I have a reasonably intelligent friend who insists he can get the same effect by opening multiple windows. Now, I have the idea that there's just so much mental overhead in opening a window that it restrains you from opening as many windows as you would tabs. I'm guessing his typical browsing sessions have a lot less windows open than I do tabs. But I'm having trouble quantifying that in a convincing way.
Can anyone explain concretely, to an engineer, what he will get out of tabs that he cannot get with windows?