From Wikipedia (adapted):Edit

The term "shoujo manga" refers to manga marketed to a female audience roughly between the ages of 10 and 18. Shoujo literally means "little girl". Shoujo manga covers many subjects in a variety of narrative and graphic styles, from historical drama to science fiction - often with a strong focus on human and romantic relationships and emotions. Strictly speaking, shōjo manga does not comprise a style or a genre per se, but rather indicates a target demographic.