Open-source projects are software initiatives where the source code is made publicly available for anyone to view, use, modify, and distribute. This collaborative approach encourages developers from around the world to contribute, leading to rapid innovation and improvement. Popular examples of open-source projects include the Linux operating system and the Apache web server. These projects often rely on community support and contributions, allowing users to report issues, suggest features, and even write code. Open-source projects can be found in various fields, including web development, data analysis, and artificial intelligence, fostering a culture of sharing and collaboration in the tech community.