On the evening of September 9, 1947, a team of engineers at Harvard University gathered around the Mark II computer, a massive electromechanical machine that filled an entire room. The machine had been malfunctioning for hours, producing erratic results that threatened to delay a critical calculation for the US Navy. Grace Hopper, a young Navy reservist and computer scientist, peered into the relay panels with a flashlight. She spotted the culprit: a dead moth, trapped between the contacts of Relay #70, its wings preventing the circuit from closing. With a pair of tweezers, she carefully removed the insect and taped it into the logbook, writing beside it: 'First actual case of bug being found.'

This moment, though small, would become legendary in computing history. Born in New York City in 1906, Grace Brewster Murray Hopper grew up in a family that encouraged her curiosity. Her father, a businessman, and her mother, a mathematician, supported her interest in how things worked. As a child, she dismantled alarm clocks and studied the gears inside, often reassembling them successfully. She attended Vassar College, earning a degree in mathematics and physics, and later completed a master's and a PhD in mathematics at Yale University. In 1943, during World War II, she joined the US Navy Reserve, hoping to contribute to the war effort.

She was assigned to the Bureau of Ordnance Computation Project at Harvard, where she worked on the Mark I computer, one of the earliest programmable calculators. Hopper's work on the Mark I and its successors, the Mark II and Mark III, placed her at the forefront of a new field. She wrote a 500-page manual for the Mark I, explaining its operations in painstaking detail. But she soon realised that programming these machines was slow and error-prone. Each new calculation required rewiring the machine or feeding it a long sequence of punched paper tape.

She attended Vassar College, earning a degree in mathematics and physics, and later completed a master's and a PhD in mathematics at Yale University.

Hopper believed there had to be a better way—a way to write instructions in a language closer to English, which the computer could then translate into its own machine code. Her colleagues were sceptical; many thought computers could only understand numbers. The turning point came in 1952, when Hopper developed the first compiler, a program she called A-0. This compiler allowed programmers to write instructions in a symbolic language, which the computer would convert into machine code automatically. When she presented her idea at a conference, she was met with disbelief.

'You can't do that,' one attendee said. 'Computers can only do arithmetic.' Hopper replied calmly, 'But we can teach them to do other things.' She spent years refining her compiler, facing resistance from both the Navy and the private sector. Many managers saw no need for a compiler, arguing that programmers could just write machine code directly. Hopper's response was to demonstrate the compiler's power through practical results. She created a version called FLOW-MATIC, which used English-like statements such as 'ADD INVENTORY TO SALES.' The US Navy adopted it for payroll and logistics, saving thousands of hours.

In 1959, she helped lead the development of COBOL (Common Business-Oriented Language), a programming language designed for business data processing. COBOL became one of the most widely used programming languages in the world, powering banking systems, government databases, and airline reservations for decades. Hopper insisted that COBOL be readable by non-programmers, so that managers could understand what the code was doing. Throughout her career, Hopper faced challenges as a woman in a male-dominated field. She was often the only woman in the room, and her ideas were sometimes dismissed because of her gender.

But she refused to be discouraged. She once said, 'The most dangerous phrase in the language is: We've always done it this way.' She encouraged young people to innovate and to question assumptions. She retired from the Navy in 1966, but was recalled a year later to help standardise the Navy's computer languages. She finally retired in 1986 as a rear admiral, the oldest active-duty officer in the US Navy at age 79. Grace Hopper's impact on computing is immeasurable. Her work on compilers and COBOL made programming accessible to millions, transforming computers from specialised research tools into engines of commerce and communication.

She received numerous awards, including the National Medal of Technology in 1991. A fun fact: the term 'computer bug' existed before Hopper's moth, but her logbook entry popularised it. Today, the moth is preserved at the Smithsonian Institution. Hopper's legacy lives on in every line of code written in a high-level language, and in the countless women and men she inspired to break down barriers and build the future.