Open Source means "open source software". This means that the software is not only supplied as an executable program, the source code of the program is also supplied, which can then also be modified and copied.
The immediate precursor of open source projects in the field of programming is the free software movement of the 1980s. Open source is subject to a special right of use, as the BITKOM definition explains: "Exploitation, duplication and processing are not permitted without reservation, because in the case of open source software the granting of rights of use is often made dependent on certain conditions. In this way, open source software can be distinguished from public domain software [...]. In the case of public domain software, the user is permitted to reproduce, distribute and modify it without restriction and without reservation."
Open source software offers a number of advantages: The software can be adapted to the needs of the user. Also, several people can work on the development of an open source program and benefit from the results of others. One is not dependent on a manufacturing company and last but not least cost savings have to be considered.