Could someone (not an engineer or architect – I don’t understand them) please explain in simple English why the buildings collapsed?

Watched it live, seen the tapes many times over, heard the explanations and theories (and even the controversy) but still can’t wrap my brain around it. The plane hit some of the top floors. There was a fire and a lot of damage. Why did the building just collapse – like in the demolitions when they blow them up setting the devices at the bottom to perfection, causing the building to implode and collapse upon itself (thus causing less damage to the immediate vicinity). I just don’t get it.