Extensibility Points
Customize your entire build process. At any stage in the build process you can trigger your own code to run any additional steps you'd like the build process to perform. All writing these steps requires you to understand is how to write MSBuild scripts. Fortunately, there are many resources available on the web. We'd start here. If you want to quickly review the built-in MSBuild tasks, check this out.
Where You Can Use This
Get The Most Out of Sitecore