The entire Linux operating system including source code can be downloaded from the internet.
In the open source world the most famous piece of software is Linux. The entire Linux operating system including source code can be downloaded from the internet. The Apache web server that is responsible for serving up a substantial amount of internet web pages is normally layered on top of the Linux operating system.
Apache may be available for Windows, kind of like Eva Gabor riding in the back of a 1948 Dodge pickup truck, and that may be where the average user most often interacts with the open source side of software. A further note to understand in the open source software world is the notion in free as in open vs free as in beer. If you get a free beer you do not have to pay for it, but open source software usually requires a costly agreement with the consultants and engineers that have the knowledge to work with the complex code in an open source application.
Open Source ERP is not a free software concept. These complex business databases could in theory be used without the computer scientists and engineers that know their inner workings, but the costs of acquiring and maintaining the highly educated workers reqiuired to do this is greater than the cost of a service agreement.