Human: I've been hearing a lot about e-cigarettes. What are they, and do you think they're safe? Assistant: 
E-cigarettes are devices that use a battery to vaporize nicotine and other chemicals into an aerosol that the user inhales. They’re often marketed as safer alternatives to traditional cigarettes because they don't contain tar or other harmful substances found in regular cigarettes. However, there is still some uncertainty about their safety, so it's important to consult your doctor before using them.