Manga and anime
Manga (漫画) are comics created in Japan, or by Japanese creators in the Japanese language, conforming to a style developed in Japan in the late 19th century. They have a long and complex pre-history in earlier Japanese art. 
Anime (アニメ) are Japanese animated productions featuring hand-drawn or computer animation. The word is the abbreviated pronunciation of "animation" in Japanese, where this term references all animation. In other languages, the term is defined as animation from Japan or as a Japanese-disseminated animation style often characterized by colorful graphics, vibrant characters and fantastic themes. Arguably, the stylization approach to the meaning may open up the possibility of anime produced in countries other than Japan. For simplicity, many Westerners strictly view anime as an animation product from Japan. 
Shotacon and Shota are words that are used to describe a type of Japanese art that depicts pre-pubescent or pubescent males in romantic or sexual situations. Homosexual relationships between boys and men is typically simply called shotacon, while heterosexual relationships between boys and women is called aneshota or straight shotacon. Shotacon falls into the larger category of Yaoi, comics about male/male love. The boys depicted in these graphic novels or anime are sometimes extremely effeminate, real “girls with dicks”.  Typically these boys dress in girls' clothes, have girls' hairstyles, and are often mistaken by the protagonist to be a girl. Other times, the boys may be depicted as typically masculine.
It is also quite common for the boys in these comic books to be given catlike features, most often cat ears and sometimes cat tails (as depicted on the image left). They are sometimes described as Uke. Uke is used in Japanese gay slang to mean the receptive partner in anal sex. They may also be described as Seme. Seme is used to describe the dominant partner of a homosexual relationship. 
The word "Shota" may be used to describe any type of anime or manga that depicts a young boy in romantic or sexual situations, and can range from being mildly romantic to having explicit sexual content. 
The words "Shota" and "Shotacon" can also be used to describe people. The words originate from a series called "Tetsujin 28 go", in which the main character was a young boy named Shotaro Kaneda. People who felt affection toward the boy were called "Shotacon", a portmanteau of the words "Shotaro" and "complex". Eventually this evolved to mean people who felt affection words any young boy in anime and manga. Meanwhile, the word "Shota" evolved to describe young boys in anime and manga whom are typically eroticized. 
Boku no Pico (My Pico) is the first installment of a series of three Japanese adult shotacon anime produced by Natural High. The producer has described it as "the world's first" shotacon animé (animated cartoon).  Boku no Pico would be considered as a typical example of this genre of art. It is the story of Tamotsu, who first sees Pico swimming nude (rear view) from a distance and later encounters him working at his grandfather’s bar. Tamotsu believes Piko to be a young girl and doesn’t discover his mistake until their first sexual encounter. Their relationship continues to develop as Tamotsu attempts to keep Pico girlish by dressing him in female clothing. Because of this and Tamotsu’s refusal to define their relationship, Pico runs away from Tamotsu and cuts his hair and puts on boys clothes. Tamotsu eventually finds Piko and they reconcile and in the end are shown playing and splashing in the sea.
Because of the current sexual hysteria in the western culture towards the sexuality of people under 18, it is uncertain if this type of art has a future even in Japan. It is almost certainly illegal to possess this art in the USA, Canada, Germany, Netherlands, Sweden, Norway, Australia, New Zealand and the UK, remaining legal in countries like Spain or Italy.  
- Manga (Wikipedia)
- Anime (Wikipedia)
- Yaoi (Wikipedia)