Ada Lovelace wrote the first computer program — for a machine that was never built

In 1843, the English mathematician Ada Lovelace translated a French article by Luigi Menabrea describing Charles Babbage’s proposed Analytical Engine — then tripled its length with her own appended notes, signed only with her initials.

The last and longest, “Note G,” laid out a step-by-step method for the machine to compute the Bernoulli numbers, a sequence from advanced mathematics. Crucially, the procedure was not a flat list of sums. It reused the same operations over and over, feeding results back in — in effect a loop — so a short set of instructions could generate term after term. Because it specified a complete sequence of operations for a machine to execute, it is widely regarded as the first published computer program, written for hardware that was never actually built.

Lovelace knew Babbage well, exchanging vivid letters in which he dubbed her the “Enchantress of Numbers.” Where he saw a calculator, she saw further.

She grasped that the engine could manipulate not just numbers but any symbol governed by rules — anticipating that machines might one day compose music or do far more than arithmetic.

Yet she drew a careful line. The engine, she wrote, “has no pretensions to originate anything”; it could only do what we know how to order it to do. That caution — later called the “Lovelace objection” — became a touchstone in debates about machine intelligence, directly challenged a century later by Alan Turing, who argued that doing exactly as instructed need not rule out surprising, even creative, results. The programming language Ada was named in her honor.