Chapter 1
Introduction to Pair Programming

There is an old saying that two heads are better than one. It may not be universally true, but modern psychology research has provided evidence of its validity in many situations.^[12] For programmers, an extra set of eyes can prevent errors and inject new ideas when working to solve tough problems. Writing code in conjunction with another programmer might help us identify edge cases or create better code designs that reduce coupling and improve cohesion—making our programs easier to maintain down the road. But there’s no need to speculate about the benefits of writing code with another programmer. Evidence from academia and industry shows that pair programming leads to better code.^[13]

Pair programming is a technique in which two programmers jointly produce one artifact, such as a design, an algorithm, or some code. Experiments have demonstrated that pairing improves design quality, reduces defects, reduces staffing risk, enhances technical skills, improves team communications, and is considered more enjoyable at statistically significant levels.^[14]

Traditionally, a pairing team would sit physically side-by-side, but improvements to screen-sharing tools, terminal-based editors, and virtualization have made it easy for pairing teams to work from different locations. Even better, studies have concluded that the quality and time benefits of remote pairing are the same as when pairing traditionally. But not all pair programming is equal—you’ve got to follow the rules.