There are a lot of different kinds of bats -- from the tiny bumblebee bat (which is the size of a jellybean and weighs less than a penny) to the huge Bismarck flying fox (with a wingspan as long as an average man).
In fact, there are over 900 different species of bats -- they make up one fifth of the world's mammals. They are the second largest group of mammals (rodents are the largest). Bats live all over the world, from the United States to Australia except for in the coldest parts.
Bats are grouped into two main groups -- the large fruit eating bats (also known as "flying foxes" or "megabats") and the smaller bats ("microbats") who eat insects, blood, fish, lizards, birds and nectar.
Megabats and microbats are quite different from one another. Microbats live worldwide, except for Antarctica and most of the arctic region. Most of the world's bats are microbats.
Megabats include nearly 200 species and live in tropical regions. They look a lot more like land mammals we're familiar with -- which is why they're called "flying foxes". Most megabats are unable to echolocate, although there are a few (like the Egyptian Rousette) that can.