Open-source software projects involve collaborative coding efforts by developers from around the world. These developers contribute to projects by writing, reviewing, and improving code that is freely available to anyone. This collaborative environment fosters innovation, learning, and the creation of high-quality software. Contributors range from experienced professionals to beginners, all working together to solve problems, add features, and enhance the overall functionality of the software. Open-source projects often rely on platforms like GitHub and GitLab to manage contributions and version control.