AWS CodeBuild is a fully managed continuous integration service that automates the build, test, and deployment of software applications for Amazon Web Services (AWS). Dan provides step-by-step instructions on how to configure AWS CodeBuild to push packages to Cloudsmith, a package repository that allows developers to easily manage and deploy their open-source projects. By integrating AWS CodeBuild with Cloudsmith, developers can automate the process of building, testing, and deploying their applications, reducing manual effort and increasing efficiency.