Mangaka (漫画家) is the Japanese word for a comic artist or cartoonist. Outside of Japan, manga usually refers to a Japanese comic book and mangaka refers to the author of the manga, who is usually Japanese. As of 2006, about 3000 professional mangaka were working in Japan.
Some artists may study for a few years at an art college, manga school, or take on an apprenticeship with another mangaka, before entering the world of manga as a professional artist. However, there are some that just start in manga, without being an assistant by applying to contests that various magazines run. For example, Naoko Takeuchi, author of Sailor Moon, who won such a contest sponsored by Kodansha, and Osamu Tezuka, creator of Astro Boy started out without being an assistant.
A mangaka will slowly rise to prominence through recognition of their ability when they spark the interest of various institutions, individuals or a demographic of manga consumers. For example, there are various contests which prospective mangaka may enter, sponsored by some of the leading manga editors and publishers in the field. They are also recognized for the number of manga they are running or have run.