Open-source software, sometimes referred as free software, is a kind of software that permits the users to run, copy, distribute, study, change and improve it. Examples include Mozilla Firefox, Android, etc. For whatever reasons, many people care about whether the software they installed is open-source, while others don't. Here I'll show you how to achieve different open source levels, from 0% open source to 100% open source.
Level -3: Proprietary Software for Everything
Use only proprietary software, even their open-source alternatives do better. The suggested brand is Microsoft, as it barely has open-source products. Make sure you run Microsoft Windows on your computer—even Mac OS X comes with too many open-source software. Use Windows Media Player as your media player, use Internet Explorer/Edge as your web browser, and use Microsoft Office as your office suite. Carefully avoid open-source software such as Bash. This is opposite to level 3.
Technically it is impossible to have 100% proprietary software, because even Microsoft Windows has included various open-source components.
Level -2: Almost Only Proprietary Software, But Open-Source Software When Required
Use proprietary software as much as possible, even their open-source alternatives do better. Run a proprietary operating system such as Microsoft Windows or Mac OS X. However, use some open-source software when required by family/co-worker/boss. For example, use Python and Ruby for work. This is opposite to level 2.
Level -1: Primarily Proprietary Software, But Open-Source Software When Preferred
Prefer proprietary software, but when their open-source alternatives do better, use the open-source alternatives instead. For example, use git instead of SourceSafe or BitKeeper. This is opposite to level 1.
Level 0: No Preference Over Open-Source or Proprietary Software
Never try to know whether an application is open-source or proprietary. If you know, try to forget them. Just use whatever you feel most comfortable with. This the most neutral position.
Level 1: Primarily Open-Source Software, But Proprietary Software When Preferred
Prefer open-source software, but when their proprietary alternatives do better, use the proprietary alternatives instead. For example, use MATLAB if Octave is far away from your need. This is opposite to level -1.
Level 2: Almost only Open-Source Software, But Proprietary Software When Required
Use open-source software as much as possible, even their proprietary alternatives do better. Run an open-source operating system such as GNU/Linux or *BSD. However, use some proprietary software when required. For example, use Skype when your family/co-worker/boss wants you to use it, and use proprietary drivers when they are required for some parts of your computer. This is opposite to level -2.
Level 3: Open Source for Everything
Use only open-source software, even their proprietary alternatives do better. The safest brand is GNU, as to be branded as a GNU software, a piece of software must be 100% open-source (free). Make sure you run an open-source operating system, such as GNU/Linux or *BSD, and only install open-source software on it. When purchasing hardware, carefully select those on which only open-source drivers are needed, such as hardware from this list. Also only purchase computers on which an open-source BIOS such as Libreboot can be installed, for example the computers listed here. This is opposite to level -3.