In science fiction books and movies, xenology is the study of aliens. Fictional scientists on intergalactic voyages might use their knowledge of xenology to better understand the unfamiliar beings they encounter along the way.
When sci-fi books and movies get specific about the science being practiced in their imagined worlds, xenology is often mentioned. Sometimes it's called xenobiology. Both words were coined using the prefix xeno-, from the Greek xénos, "alien." Xenology first appeared in 1940s and 50s science fiction magazines, but it became more popular after Robert Freitas published a book in 1979 called Xenology, described as "a handbook to alien life."