Approximately 70 percent of bat species are insectivores, meaning that they feed off of insects. Most of the remaining bat species are frugivores, creatures that feed on fruits. Only three species actually feed upon other animals. This is actually very interesting because the vampire bat is the only parasitic mammal. However, you have nothing to fear from these few lone, carnivorous bats. Vampire bats mostly feed on large animals, humans aren't usually a target.
One of the reasons that I think bats are misunderstood is that people actually don't understand them. I'm talking about their general biology, diets and behavioral patterns. It is a common misconception that all bats are blind. This just isn't the case. There are two major types of bats, megabats and microbats (megachiroptera and microchiroptera). None of the bats in either of these two groups are blind. Microbats use echolocation to locate their prey, but this doesn't mean that they can't see. Microbats have a poorly developed visual cortex, so they cannot rely on sight while hunting. Megabats do have well developed visual cortexes, meaning that they can see very well. Megabats generally eat fruits or nectar while microbats go after insects, thus explaining their relative eyesight. Bats also have a well developed sense of smell that helps them find flowers and navigate, but you rarely hear about that.
Giant golden crowned flying fox, largest bat
Bat's wings are one of their most interesting attributes. They don't have feathers, just a very thin membrane stretched between their fingers. The thinness of this membrane allows bats to maneuver very well, much better than a bird ever could. Because of how thin this membrane is, it is very fragile, which means that bats have to be careful not to tear their wings. This task is a lot easier than it sounds however. Bat's wings are capable of healing very fast, meaning that small tears will repair themselves before any significant damage can be done. Bats also have sensory receptors at the base of little hairs on their wings. These receptors give them information about the wind blowing past their wings so that they can fly more efficiently, and detect whenever an insect hits them.
Kitti's hog-nosed bat, possibly the worlds smallest bat
Bats are pivotal to the global ecosystem. Because of their ability to fly, bats have spread to almost every corner of the world, only arctic regions and obscure islands are free of them. Bats spread seeds from the fruits that they eat, aiding in the reproduction of fruit bearing plants. Some tropical plants even rely solely on bats to spread their seeds. Nectar feeding bats fertilize plants by carrying pollen from one plant to another, and insect eating bats are pivotal to controlling the global bug population. Without bats, the world would be a very different place, and if they were to all suddenly die, our ecosystem would be thrown into turmoil. We need bats.