ROS is a large project that has many ancestors and contributors. The need for an open collaboration framework was felt by many people in the robotics research community. The effort was boosted by countless researchers who contributed their time and expertise to the core of ROS and its fundamental software packages. Throughout, the software was developed in the open using the permissive BSD open source license, and it gradually became widely used in the robotics research community.
The ROS ecosystem now consists of tens of thousands of users worldwide, working in domains ranging from tabletop hobby projects to large industrial automation systems.