Koko, western lowland gorilla and user of American Sign Language (born 1971)

Hanabiko, nicknamed "Koko" was a female western lowland gorilla born in the San Francisco Zoo and cross-fostered by Francine Patterson for use in ape language experiments. Koko gained public attention as the subject of two National Geographic cover stories and, in 1985, the best-selling children's picture book, Koko's Kitten. Koko became the world's most famous representative of her critically endangered species.

The western lowland gorilla is one of two Critically Endangered subspecies of the western gorilla that lives in montane, primary and secondary forest and lowland swampland in central Africa in Angola, Cameroon, Central African Republic, Republic of the Congo, Democratic Republic of the Congo, Equatorial Guinea and Gabon. It is the nominate subspecies of the western gorilla, and the smallest of the four gorilla subspecies.

American Sign Language (ASL) is a natural language that serves as the predominant sign language of Deaf communities in the United States and most of Anglophone Canada. ASL is a complete and organized visual language that is expressed by employing both manual and nonmanual features. Besides North America, dialects of ASL and ASL-based creoles are used in many countries around the world, including much of West Africa and parts of Southeast Asia. ASL is also widely learned as a second language, serving as a lingua franca. ASL is most closely related to French Sign Language (LSF). It has been proposed that ASL is a creole language of LSF, although ASL shows features atypical of creole languages, such as agglutinative morphology.

June 19 is the 170th day of the year in the Gregorian calendar; 195 days remain until the end of the year.