An EV basically is any vehicle that plugs into an outlet to get power. There are two main types:
Battery Electric Vehicles (BEVs)
These use no liquid fuel and rely solely on a battery pack and electric motor. Because of this, their range is limited to the amount of energy stored in the battery pack. The new Nissan Leaf has an estimated range of 107 miles. The Tesla Model S has a range of up of 350 miles depending on the model and driving conditions.
Plug-in Hybrid Electric Vehicles (PHEVs)
Plug-in hybrid cars differ from their hybrid brethren in that they do just that plug in. So with these cars, drivers get fully-electric miles before the car uses a drop of liquid fuel. The 2017 Chevy Volt gets about 53 miles of fully-electric range, so if your daily commute is less than that, you will only be driving on electric. The advantage of PHEVs over BEVs is that these cars can go much farther by switching over to gas after the battery pack is depleted. So, they are useful both as a daily driver and for longer road trips