History of software

The historical development of instructions and systems that make computers perform tasks, from early machine code to modern software engineering and applications.

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Ada Lovelace: An English mathematician who wrote notes describing how Charles Babbage’s Analytical Engine could manipulate symbols. Her 1843 notes included an algorithm intended for execution by a general-purpose machine.
Machine code: The binary instructions a processor executes directly. Early software had to express operations in the exact instruction forms understood by each machine.
Grace Hopper: An American computer scientist who helped develop early compilers and the COBOL programming language. Her compiler work advanced the idea that programs could be written in language closer to human notation.
Software engineering: The discipline of designing, building, testing, and maintaining software systematically. Growing software complexity prompted methods and institutions beyond individual programming.
Punch card: A stiff paper card whose holes encode data or instructions for processing equipment. Punched cards were a dominant medium for entering programs and data before interactive terminals.
Analytical Engine: Charles Babbage’s proposed mechanical general-purpose computer, designed with memory, a processor, and programmable operations. Its design anticipated stored operations and conditional control before electronic computers existed.
Assembly language: A low-level programming language whose symbolic instructions correspond closely to a processor’s machine instructions. Assemblers replaced error-prone numeric instruction entry with readable operation names and labels.
John Backus: An American computer scientist who led the IBM team that created FORTRAN. His team demonstrated that compiled high-level languages could compete with hand-written machine code.
Software crisis: A term for recurring failures to deliver complex software on time, within budget, and to specification. The problems associated with large projects helped motivate software engineering conferences and practices.
Time-sharing: A computing method that rapidly switches a processor among users or tasks, creating interactive access. It replaced batch-only workflows with direct interaction on shared computers.