Much of a programmer's time is taken up by the isolated pursuit of writing code. This is, to many programmers, their ideal situation; they are able to block out the rest of the world and find fluid productivity, writing logic with speed and fluency. One risk of this isolation, however, is that vital knowledge of a code base or system can accrue in the minds of the few. Without being distributed, there is a risk that the code base will become increasingly specialized and complex, limiting the ability of newcomers and colleagues to navigate it with ease. For this reason, it is essential to consider how to transfer knowledge effectively between programmers.

As discussed previously in the book, we already have a number of formal ways to transfer knowledge regarding a piece of code:

• Via documentation, in all its forms
• Via the code itself, including comments
• Via tests, including unit and E2E variants

Even though these mediums, if built correctly, can be effective in relaying knowledge, there appears to always be a need for something else. The basic human convention of ad hoc communication is a method that has stood the test of time and still remains one of the most effective methods. 

One of the best ways to learn about a new code base is through pair programming, an activity in which you sit alongside a more experienced programmer and collaborate together on bug fixes or feature implementations. This is especially useful for the unfamiliar programmer, as they are able to benefit from the existing knowledge and experience of their programming partner. Pair programming is also useful when there is an especially complex issue to solve. Having two or more brains tackling the problem can drastically increase problem-solving ability and limit the possibility of bugs.

Even outside of pair programming, generally having a Q&A or teacher-student dynamic can be very useful. Setting aside time to talk to individuals who have the knowledge you desire and asking them pointed but exploratory questions will usually yield a lot of understanding. Do not underestimate the power of a focused conversation with someone that has the knowledge you desire.