The equality sign (=) is a mathematical symbol used to indicate that two expressions have the same value. It was first introduced by the Welsh mathematician Robert Recorde in 1557. The sign is essential in equations, allowing us to express relationships between numbers and variables clearly. In mathematics, the equality sign helps in solving problems and verifying solutions. For example, in the equation 2 + 2 = 4, the equality sign shows that the left side (2 + 2) is equal to the right side (4). This symbol is fundamental in algebra, calculus, and many other areas of mathematics.