A slide rule is a mechanical analog device used for mathematical calculations, particularly multiplication, division, and functions like logarithms and trigonometry. It consists of a ruler with a sliding central strip, allowing users to align numbers and perform calculations visually. Slide rules were widely used by engineers and scientists before the advent of electronic calculators. Although slide rules have largely been replaced by digital technology, they remain a significant part of mathematical history. Many enthusiasts still appreciate them for their educational value and the understanding of mathematical concepts they provide. Notable figures like William Oughtred contributed to their development in the 17th century.