Well-written article basically summarizing the thoughts of great software developers versus those who just write code to get something working.
A “full-stack programmer” is a generalist, someone who can create a non-trivial application by themselves. People who develop broad skills also tend to develop a good mental model of how different layers of a system behave. This turns out to be especially valuable for performance & optimization work. No one can know everything about everything, but you should be able to visualize what happens up and down the stack as an application does its thing. http://calendar.perfplanet.com/2010/the-full-stack/