You might be thinking about a "Plug-In Hybrid" which can provide an extra 30 miles or so on electric only.
A regular "Hybrid" has "Regenerative Braking." Whenever you brake or coast, a generator recharges the battery pack. You're able to see it on a dashboard indicator.
One of my concerns was, "What if I don't brake for a long time - like on a long freeway drive; won't the batteries get too low to drive the car?"
The manual explains it. "When the battery pack gets below a certain point, the gas engine takes over completely, so you'll never be without power."