Highly Cited Researchers (HCR) from Clarivate Analytics (formerly known as the Intellectual Property & Science Business of Thomson Reuters) is an annual list recognizing influential researchers in the sciences and social sciences from around the world. The 2019 list contains about 6,000 Highly Cited Researchers in 21 fields (those used in Clarivate Analytics Essential Science Indicators, or ESI) of the sciences, social sciences and across several fields. The list focuses on contemporary research achievement: only highly cited papers in science and social sciences journals indexed in the Web of Science Core Collection during the past 10-year period were surveyed. Highly cited papers are defined as those that rank in the top 1% by citations for field and publication year.