Source code
The first programmable computers, which appeared at the end of the 1940s,[2] were programmed in machine language (simple instructions that could be directly executed by the processor).
[5][6] As instructions distinct from the underlying computer hardware, software is therefore relatively recent, dating to these early high-level programming languages such as Fortran, Lisp, and Cobol.
[10] Software developers often use configuration management to track changes to source code files (version control).
[13] Computer programmers may find it helpful to review existing source code to learn about programming techniques.
[13] The sharing of source code between developers is frequently cited as a contributing factor to the maturation of their programming skills.
[15] Companies often keep the source code confidential in order to hide algorithms considered a trade secret.
IDEs typically have several features built in, including a source-code editor that can alert the programmer to common errors.
[24] The purpose of this phase is often to verify that the code meets style and maintainability standards and that it is a correct implementation of the software design.
[26] Debuggers are tools that often enable programmers to step through execution while keeping track of which source code corresponds to each change of state.
[22][28] Software quality is an overarching term that can refer to a code's correct and efficient behavior, its reusability and portability, or the ease of modification.
[30] Higher quality code will reduce lifetime cost to both suppliers and customers as it is more reliable and easier to maintain.
[33] Following coding conventions such as using clear function and variable names that correspond to their purpose makes maintenance easier.
[32] Technical debt is incurred when programmers, often out of laziness or urgency to meet a deadline, choose quick and dirty solutions rather than build maintainability into their code.
[42] Although the term open-source software literally refers to public access to the source code,[43] open-source software has additional requirements: free redistribution, permission to modify the source code and release derivative works under the same license, and nondiscrimination between different uses—including commercial use.
