For the benefit of a rather thick, old lady behind the times, could someone be kind enough to explain to me about these electronic cigarettes and how they work? My husband went on a bus to London recently and said people were smoking plastic things 'with steam coming out'. And I'm sure I've heard they can explode or ignite or something. And what exactly do nicotine addicts get from these strange devices? I'd be most interested to learn all about them.