Pair programming is a software development technique in which two programmers work together at one workstation. One, the driver, writes code while the other, the observer or navigator, reviews each line of code as it is typed in. The two programmers switch roles frequently. While reviewing, the observer also considers the "strategic" direction of the work, coming up with ideas for improvements and likely future problems to address. This is intended to free the driver to focus all of their attention on the "tactical" aspects of completing the current task, using the observer as a safety net and guide. Economics Pair programming increases the person-hours required to deliver code compared to programmers working individually. However, the resulting code has fewer defects. Along with code development time, other factors like field support costs and quality assurance also figure into the return on investment. Pair programming might theoretically offset these expenses by reducing defects in the programs. In addition to preventing mistakes as they are made, other intangible benefits may exist. For example, the courtesy of rejecting phone calls or other distractions while working together, taking fewer breaks at agreed-upon intervals, or shared breaks to return phone calls (but returning to work quickly since someone is waiting). One member of the team might have more focus and help drive or awaken the other if they lose focus, and that role might periodically change. One member might have knowledge of a topic or technique that the other does not, which might eliminate delays to find or testing a solution, or allow for a better solution, thus effectively expanding the skill set, knowledge, and experience of a programmer as compared to working alone. Each of these intangible benefits, and many more, may be challenging to accurately measure but can contribute to more efficient working hours. Design quality A system with two programmers possesses greater potential for the generation of more diverse solutions to problems for three reasons: the programmers bring different prior experiences to the task; they may assess information relevant to the task in different ways; they stand in different relationships to the problem by virtue of their functional roles. In an attempt to share goals and plans, the programmers must overtly negotiate a shared course of action when a conflict arises between them. In doing so, they consider a larger number of ways of solving the problem than a single programmer alone