Refers to products or information controlled by one entity, without sharing rights with others. Their proprietary recipes are closely guarded secrets.
Pro Tip 2/3
Not Open Source
Unlike open-source software, proprietary cannot be freely modified or distributed. You can't alter proprietary software to suit your needs like you can with open source.
Pro Tip 3/3
Licensing Required
You may need to pay to use proprietary items legally because they're not free to use. You must purchase a license to use this proprietary font in your publication.