Literally "Girl - Love", Shōjo
-ai refers to stories that feature romantic ties between female characters. Not to be confused with Yuri, which refers to lesbian pornography. The differences are that Shōjo-ai focuses on the relationship and often does not contain any explicit material (the romantic relations may even exclude sex).
Similar to the situation with yaoi / shōnen-ai, it has become increasingly popular in North America for shōjo-ai titles to be labelled "yuri," both by fans and distributors.
See also: shōjo
, yuri, shōnen-ai