The HTTP core module is the component that contains all of the fundamental blocks, directives, and variables of the HTTP server. It's enabled by default when you configure the build (as described in Chapter 1, Downloading and Installing Nginx), but it's actually optional—you can decide not to include it in your custom build. Doing so will completely disable all HTTP functionalities, and all of the other HTTP modules will not be compiled. Obviously, if you purchased this book, it's highly likely that you are interested in the web-serving capacities of Nginx, so you will have this enabled.
This module is the largest of all standard Nginx modules—it provides an impressive number of directives and variables. In order to understand all of these new elements and how they come into play, we first need to understand the logical organization...
