POSTGRESQL is open source software. The term open source software often confuses people. With commercial software, a company hires programmers, develops a product, and sells it to users. With Internet communication, there are new possibilities. In open source software, there is no company. Capable programmers with interest and some free time get together via the Internet and exchange ideas. Someone writes a program and puts it in a place everyone can access. Other programmers join and make changes. When the program is sufficiently functional, they advertise the program's availability to other Internet users. Users find bugs or missing features and report them back to the developers, who enhance the program.
It sounds like an unworkable cycle, but in fact it has several advantages: