Kodomo creators typically aim their work at children. It is non gender-specific and is traditionally educational, teaching social skills and manners. Kare Kano and Kirarin Revolution are examples of kodomo anime.
Aimed at adolescent boys ages 10 to 17, shounen is a manga type of anime. Characteristics of shounen are fighting and beautiful strong female roles. Comedic plots and undertones of strong friendships are also typical of shounen. Popular shounen anime are Dragon Ball and Yu-Gi-Oh!
Shojo is a type of manga. The shojo target audience is girls aged 13 to 17. The main focus is on emotions, interpersonal relationships and friendships. Ai no Wakakusa Monogatari ,Akage no An, Candy Candy and Dream Hunter REM are shojo anime.
Ecchi anime are strong and sexual in nature and not for a younger audience. The females are scandalously clad and the topic matter usually turns sexual without showing intercourse. It is similar to hentai but a more toned down version. If hentai were rated X, then ecchi would be rated R.
Seinen is for young men ages 18 to 25. Themes and topics vary and anything goes in seinen anime. Some popular seinen anime are Buddha, Kachou Shima Kosuke and Tetsuwan Girl.
Hentai is anime pornography. On-screen sexual acts are depicted and the unimaginable and impossible can occur. Sex with monsters, demons, and aliens is common. "Tentacle porn" is a part of hentai.
Harem and reverse harem have the main character surrounded by multiple characters of opposite sex, usually three or more, in a romantic way. There is often a love triangle depicted. In harem, the main character is a male. In reverse harem, the main character is a female. Popular harem anime include Fruits Basket and The Wallflower.
Josei is for females ages 18 plus. The topic matter is true to life and usually of a mature nature. Popular josei anime include Honey and Clover and Nana.