The concept of zero as both a placeholder and a number in its own right represents one of the most significant intellectual achievements in the history of mathematics. Ancient civilisations, including the Babylonians, developed early placeholder symbols to indicate an absence of value in a particular position within a number, but they largely stopped short of treating zero as a number with its own independent mathematical properties. It was mathematicians in India, particularly by the 7th century CE, who first formally treated zero as a number that could be added, subtracted, and used in calculations, laying crucial groundwork for the broader number system used today. This concept later spread westward through the Islamic world, where scholars further developed and refined mathematical techniques involving zero, before eventually reaching Europe through trade and translated scholarly texts. European mathematicians initially met the concept with considerable resistance; some medieval scholars regarded zero with suspicion, associating it with philosophical or even theological concerns about the nature of nothingness. Despite this early resistance, the practical advantages zero offered for calculation, particularly within the broader positional number system, eventually proved too significant to ignore. By the Renaissance, zero had become a fully integrated part of European mathematics, essential to the development of algebra, calculus, and eventually computer science, in which it plays an absolutely foundational role.