Understanding teen sexting

As a parent of a teenager, is "sexting" something that I need to be concerned about? I've heard a few stories about this on the news, but I've never felt that my daughter would be susceptible to temptations of this kind. We haven't talked about it because I'm really not up to speed on the technology, nor do I know exactly what's involved. Besides, she's a really good kid. Do you think I should bring up the subject with her?