Snippets from <http://lwn.net/Articles/662106/>: Is there anybody out there who understands the entire kernel? Linus said that nobody does. There are some people who have a good overview of the whole kernel, and Linus, at least, generally knows who to blame for any specific problem. But with a project the size of the kernel it's not possible for anybody to have a deep understanding of the whole thing. ... With regard to how an aspiring kernel developer should start, Linus has always said the same thing: he can't tell developers what to do. It is important, instead, that developers work on things they *want* to do. ... How many kernel compiles has he done? It used to take about twelve minutes to compile a kernel; over time, the kernel has gotten bigger, but the hardware has gotten faster; the current time is about 22 minutes for an allmodconfig kernel. He does about ten builds per day during the merge window, a couple otherwise. Kernel development has been happening for about 8800 days; the bottom line, Linus guessed, was about 100,000 compiles. ... What about the Git project — what made that project successful? Linus gave a lot of credit to BitKeeper which, despite its licensing issues, changed how the kernel community did development. Git, of course, is an [Linus Torvalds] improvement on BitKeeper, but BitKeeper showed the benefits of distributed development when nobody else was working in that area. Once Git was around, its use by the kernel community helped it to spread quickly. Its immutable object model turned out to make it easy for service providers to use, enabling companies like GitHub. Ten years ago, developers were resistant to thinking about source-code management issues; Git forced them to look at it and to realize how much better distributed source-code management is. Git was not the first in this area, but it was the one that created wide awareness of a better way of doing things.