Build tools are software applications that automate the process of compiling source code into executable programs. They help developers manage tasks such as compiling, linking, and packaging code, making it easier to create software efficiently. Common build tools include Maven, Gradle, and Make. These tools streamline the development workflow by handling dependencies and ensuring that the correct versions of libraries are used. They can also run tests and generate documentation, allowing developers to focus on writing code rather than managing the build process. Overall, build tools enhance productivity and maintainability in software development.