A Makefile is a special file used by the make build automation tool to manage the compilation of programs. It contains a set of rules and dependencies that specify how to compile and link the program's source code files. By using a Makefile, developers can automate the build process, ensuring that only the necessary files are recompiled when changes are made. Makefiles help streamline the development workflow by allowing developers to define targets, such as executable files or libraries, and the commands needed to create them. This reduces the complexity of managing multiple source files and simplifies the process of building software projects, especially in larger codebases.