Software testing developed alongside software development, which began shortly after World War II. Tom Kilburn, an English computer scientist, is credited with creating the first piece of software, which debuted on June 21, 1948, at the University of Manchester. It used machine code instructions to perform mathematical calculations.
Debugging was the primary method of testing at the time, and it remained so for the next two decades. By the 1980s, development teams had shifted their focus from isolating and fixing software bugs to testing applications in real-world scenarios. It laid the groundwork for a broader perspective on testing, which included a quality assurance process as part of the software development life cycle.