If you see an “i” in any of our model name (C7i, M7i, V7i, ect.) that means that bike comes equipped with an internal hub. With an internal gear hub, the gearing system is encased in a sealed mechanism and the chain remains on the same gear at all times. You don't have to fret about the the chain falling off, or dirt and grime entering the hub and causing damage. For the average cyclist, a quality internal gear hub lasts a lifetime if properly maintained.
The real benefit to an internal hub is that it allows you to shift while coasting, backpedaling, or even at a complete standstill. This comes in handy when riding in stop and go traffic in the city. It’s also makes climbing a lot easier. With an exterior gear or derailleur, you can see the chain on the outside of the gears and is most likely the type of gearing you had on your very first bike. Derailleurs are lighter in weight and a bit more responsive, but they do require more maintenance and you must be pedaling while shifting.