What is "open source"?
Open-Source is software whose program code can be viewed publicly and by third parties. Open source does not automatically mean free, even if there are many free open source applications.
Free open source applications include many, but not all, Linux distributions, the Libre Office suite of applications, the Firefox Internet browser, the Python and PHP programming languages, and the Gimp graphics program.
Many web applications are also open source programs, for example Wordpress or Shopware. Often there is also a so-called "Community Edition" that is available free of charge and an extended version for which you do not necessarily have access to the entire source code.
Nor does open source mean that you can do what you want with the code. There are a variety of license models for open source. You can find out more about this, for example here.
So what are the advantages of open source?
In addition to the cost savings with free software, there is a particular advantage in security. Only when the source code is exposed can one check or have it checked whether a software actually does that and only does what it should.
With closed source software, you never know who is accessing your data - and to what extent. Most programs you can buy today connect to a manufacturer's server over the Internet, and data is readily resold. But maybe it is also your customer database or the plans for a product you have developed that are transmitted there.
Open source is a security advantage.
The other advantage of open source is, of course, that open source software can be modified and adapted to your needs. That is not the norm, and it is not cheap either, but there are certainly cases in which it makes sense.
In addition, open source software also knows the data format in which data is stored. You do not lose your data if the software is not further developed or you do not have to work forever with an outdated program or you are bound to a certain operating system. And you can have software developed yourself that processes this data.
Open source makes you flexible and independent.