Babbage’s Analytical Engine was first described in 1837. It emerged as a more ambitious successor to his Difference Engine, which was designed for a narrower class of numerical calculations.
The Analytical Engine was intended to be a general-purpose mechanical computer. Babbage’s design included a “store” for memory, a “mill” for arithmetic and processing, punched cards for programs and data, and mechanisms for conditional branching and loops. These features distinguish it from a simple calculator.
Babbage continued revising the design for decades, and the complete machine was never built during his lifetime. The date therefore refers to the first description of the design, not to the completion or first operation of a physical engine.
The machine’s ideas became better known through Luigi Federico Menabrea’s 1842 French description and Ada Lovelace’s expanded 1843 translation. Lovelace’s notes included a Bernoulli-number algorithm often called the first published computer program. Babbage died in 1871, which explains why that year is sometimes confused with the engine’s history.