Who is credited with inventing the equals sign (=)?

The equals sign (=) is credited to Robert Recorde, a Welsh mathematician, who introduced it in the 16th century. He used this symbol in his book “The Whetstone of Witte,” published in 1557, to simplify the way equations were written. Recorde chose the symbol of two parallel lines because he believed that "no two things can be more equal." His innovation provided a clear and concise way to denote equality in mathematical expressions, which has since become a universal standard in mathematics.

In contrast, while Isaac Newton made significant contributions to mathematics and physics, he was not associated with the invention of the equals sign. Albert Einstein, known for his work in theoretical physics, and René Descartes, recognized for his work in philosophy and Cartesian coordinates, also did not contribute to the introduction of the equals sign. Recorde's establishment of this symbol was a pivotal moment in mathematical notation, which has facilitated clearer communication of mathematical ideas throughout the centuries.