William Oughtred (1574-1660) was an English mathematician best known for inventing the slide rule, a tool used for calculations before the advent of calculators. He also contributed to the development of logarithms, which simplify complex calculations by transforming multiplication and division into addition and subtraction. Oughtred was a teacher and wrote several influential mathematical texts, including "The Circle of Proportion" and "The Art of Conjecturing." His work laid the foundation for future advancements in mathematics and education, influencing notable figures such as Isaac Newton and John Napier, the latter known for popularizing logarithms.