This is part 1 of a series of three lectures entitled Data in Context given by Prof. De Weerdt at the Summer School for Quantitative History held at Shanghai Jiao Tong University, Shanghai, China, from July 6 to 16, 2024. The Summer School is jointly organized by the Department of History at Shanghai Jiao Tong University, the Center of Quantitative History at HKU Business School, and the School of History at Renmin University of China, in collaboration with the International Society for Quantitative History and the HK Institute for Humanities and Social Sciences.