Yaoi would be guyxguy and Yuri is girlxgirl. These categories can go anywhere from a single KISS to sex so be careful and research a show/manga before Du watch/read it in case it has something Du might feel uncomfortable seeing. Then there is Shounen-ai (Boys-love literally) which is still guyxguy but there is no sex oder harsher activity involved. Only kisses and snuggles are involved here. The same goes for Shoujo-ai (Girls-love). No sexual activity involved except for Küssen and snuggling. =] Hope that helped!