Programmers mentally divide code into three layers: their own code, the libraries and tools they interact with, and the environment. Unfortunately, the environment is the layer they care about least. My mission is to convince you that the environment is interesting and worth caring about. Did you know that the environment metaphor is very inaccurate? It's really the foundation supporting your code. And then, there are additional environments you should be aware of: the social environments of developers and users, society at large, the physical environment of our computing systems. Are you ready to become an environmentalist?