Though not a computer in the modern sense, the abacus holds the title of "world's first computer" for its ability to perform calculations. Dating back to 2400 BC in Mesopotamia, this ancient marvel used beads sliding on rods to represent numbers. By manipulating these beads, users could add, subtract, and even perform more complex calculations using positional notation, a precursor to our modern system. While lacking the programmability and processing power of modern computers, the abacus laid the groundwork for centuries of computing advancements, earning its place as a true pioneer in the history of technology.