“our explosive growth was slowing down our pace of innovation. We were spending more time coordinating and less time building. More features meant more software, written and supported by more software engineers, so both the code base and the technical staff grew continuously. Software engineers were once free to modify any section of the entire code base to independently develop, test, and immediately deploy any new features to the website. But as the number of software engineers grew, their work overlapped and intertwined until it was often difficult for teams to complete their work independently. Each overlap created one kind of dependency, which describes something one team needs but can’t supply for itself. If my team’s work requires effort from yours—whether it’s to build something new, participate, or review—you’re one of my dependencies. Conversely, if your team needs something from mine, I’m a dependency of yours. Managing dependencies requires coordination—two or more people sitting down to hash out a solution—and coordination takes time. As Amazon grew, we realized that despite our best efforts, we were spending too much time coordinating and not enough time building. That’s because, while the growth in employees was linear, the number of their possible lines of communication grew exponentially. Regardless of what form it takes—and we’ll get into the different forms in more detail shortly—every dependency creates drag. Amazon’s growing number of dependencies delayed results, increased frustration, and disempowered teams.”