The domestic chicken (Gallus gallus domesticus) is a domesticated subspecies of the red junglefowl (Gallus gallus), a species of bird in the family Phasianidae. The red junglefowl is native to Southeast Asia, and the chicken was first domesticated in China around 10,000 years ago. Chickens have since become one of the most common and widespread birds on Earth, and have been introduced to every continent except Antarctica.

The domestication of chickens has had a profound impact on the world. Chickens are a source of food, eggs, and feathers, and have been used for religious and cultural purposes. The chicken meat industry is a major part of the global food economy, and eggs are a staple food in many cultures.

The domestication of chickens has also had a significant environmental impact. Chickens have been introduced to many ecosystems where they were not native, and have sometimes become invasive species. Chickens can compete with native birds for food and habitat, and can also spread diseases.

However, the domestication of chickens has also had some positive environmental impacts. Chickens can help to control pests and insects, and can also be used to improve soil quality.

Overall, the domestication of chickens has had a major impact on the world, both positive and negative. Chickens have become one of the most common and widespread birds on Earth, and have played a significant role in human history and culture.