5 Things You Need to Know About E-Cigarettes

The electronic cigarette was invented in the 1960s, but it didn't really take off until a decade ago. Currently, there are more than 250 brands of "e-cigarettes" available in such flavors as watermelon, pink bubble gum and Java, and in more colors than the iPhone 5C.

The Tobacco Vapor Electronic Cigarette Association estimates about 4 million Americans now use battery powered cigarettes. They project sales of the devices to cross the 1 billion mark by the end of this year. Here, a look at the e-smoke trend, the good, the bad and the unknown.