Historical letters are written communications that provide insight into the thoughts, feelings, and events of the past. They can be personal correspondences between individuals, such as letters from Abraham Lincoln to his family, or official documents like those exchanged between leaders during significant events, such as the American Revolution. These letters serve as valuable primary sources for historians and researchers. These documents often reveal the social, political, and cultural contexts of their time. They can help us understand historical figures, such as Marie Curie, and their contributions, as well as the everyday lives of ordinary people. Analyzing historical letters allows us to connect with the past in a meaningful way.