The Chinese Academy of Sciences (CAS; ), with historical origins in the Academia Sinica during the Republic of China era, is the national academy for the natural sciences of the People's Republic of China (PRC). Collectively known as the "Two Academies (两院)" along with the Chinese Academy of Engineering, it is an institution of China, functioning as the national scientific think tank and academic governing body, providing advisory and appraisal services on issues stemming from the national economy, social development, and science and technology progress. It is headquartered in Beijing, with branch institutes all over mainland China. It has also created hundreds of commercial enterprises, with Lenovo being one of the most famous.