Pair Programming is a core practices of extreme programming and literally means that all production software is written by two programmers, sitting side by side, at the same machine. This practice ensures that all production code is reviewed by at least one other programmer, and results in better design, better testing, and better code.
The actual practice of pairing requires programmers to frequently (daily or multiple times per day) swap pairs to promote sharing of knowledge throughout the team. As pairs switch, everyone gets the benefits of everyone’s specialised knowledge.
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