Pair Programming

In XP, all production software is written by two programmers sitting at the same machine. Pair programming provides instant review: Every line of code in the whole system is examined by at least two pairs of eyes. Pair programming results in rapid learning, which in turn increases your schedule flexibility: More programmers are equipped to sign up for more stories.

Is Pair Programming Essential?

You can probably survive without it. However, without pair programming, you'll lose flexibility, you'll need to come up with other ways of communicating the design among the programmers, and you'll see a decline in code quality. You won't die, but your project will suffer.