Bats, a group of very unique flying mammals appeared about 65 million years ago when there were still dinosaurs, with more than 1,100 species, has colonized most of the planet. This work brings us closer to their origins, their life cycles, performing migrations, and viral diseases that can be transmitted by them. It also gives the geographical distribution of the species in Catalonia and the Balearic Islands. Finally, it also brings us to the strong impression that bats have left in popular culture and the close relationship between biodiversity and cultural diversity. The book collects the whole results of 26 years of bats research conducted by the authors.