Useful words to know
Anime--Japanese cartoons or animated movies. In Japanese, means simply any comic or cartoon, but in English, it's a specific genre of Japanese origin.
Dojinshi--'what-if' stories, often written by fans. They don't count as part of the story; just fun fantasies. They range from funny to graphic.
Ecchi--"fresh" content; sexual, but not graphic. Sometimes there isn't any difference between it and hentai.
Hentai--graphically sexual in content.
Japanimation--you might see this word used for anime. Don't, however, use it yourself; it's not very polite (can be spelled Jap-animation) and fans all know that anime is the correct term.
Manga--Printed comic books. A popular series will usually have both anime and manga versions, and sometimes there are important differences between the two.
Mecha--generic term for anything mechanized or technological, especially series with giant robots. 'Escaflowne' is a medieval/mecha series.
Otaku--a fan. In Japanese, it means something more like 'fanatic' and has a bad connotation, but in the US, people use it with pride.
OVA--Original Anime Video. Describes anime that goes straight to video (most of it).
Senshi--warrior/soldier. Sailor Senshi are the Sailor Scouts (see Sailor Moon).
Shojo--girl
Shonen--boy
Shojo manga is aimed at girls, and often has romantic overtones, while shonen manga is considered boyish and generally has more action and violence. The two genres have largely merged, but there are still differences.