Lovelace’s explanatory notes on Menabrea’s paper were labeled from A to G. The seven notes were appended to her English translation of Menabrea’s account of Babbage’s Analytical Engine and progressively explained the machine’s capabilities and implications.
The final note, Note G, is the best known. It presented a detailed method for using the Analytical Engine to calculate Bernoulli numbers, making it an important early example of a published algorithm intended for a programmable machine. The calculation required repeated operations and temporary values, illustrating why the Analytical Engine was more than a fixed-purpose calculator.
The A-to-G sequence also helps distinguish Lovelace’s work from Babbage’s earlier Difference Engine. Her notes focused on the Analytical Engine, whose proposed design included a “mill” for operations, a “store” for holding values, and punched cards for instructions. Note G is often called the first computer program, though historians debate how credit should be divided between Lovelace and Babbage.