Manga
Manga are Japanese comics, usually serialized in magazines and collected in numbered volumes, printed in black and white and read from right to left.
Where the word comes from
Japanese 漫画, roughly "whimsical pictures". The word was popularised in the early nineteenth century by Hokusai's sketchbooks, the Hokusai Manga, long before it meant comics.
In depth
Manga is the Japanese word for comics, and outside Japan it names comics from Japan. Most manga first appears in chapters in weekly or monthly magazines, then is collected into volumes (tankōbon) that are sold as books. Pages are usually black and white and read from right to left.
After the war
The modern form took shape after the Second World War. Osamu Tezuka, often called the god of manga, brought cinematic pacing and long stories to the medium with works such as New Treasure Island (1947) and Astro Boy. From the 1960s onward, magazines for different audiences — boys, girls, adult men, adult women — built the market that exists today.
Sorted by readership
Manga is organised by demographic rather than genre: shōnen, shōjo, seinen and josei name the audience of the magazine a series ran in. Within each, every genre exists.
In English
English translations grew from the 1980s and became a mass market in the early 2000s, when publishers began keeping the original right-to-left orientation. Manga now accounts for a large share of graphic novel sales in the United States.
Where it appears
Astro Boy by Osamu Tezuka. the post-war series that shaped modern manga
One Piece by Eiichiro Oda. a long-running shōnen series, among the best-selling comics ever
What it means today
New readers do best choosing by genre and starting at volume 1. The demographic label tells you the intended reader, not whether you will like it.