Disclaimer

I am not a lawyer

Licenses are legal documents

Seek advice if needed

Free vs. Free

• Without Cost
  (Free as in Food)
• Without Restriction
  (Free as in Speech)

Free != Free

Copyright

No license implies all rights reserved!

Public Domain

• Least Restrictive
• Useable by Anyone
• Can Use for Any Purpose
• Allows Reselling & Relicensing
• Creative Commons CC0
• GitHub Unlicense

Permissive License

• Few Restrictions
• Maintain License
• No Warranty or Liability
• Allows Reselling & Relicensing
• MIT, BSD, Apache Licenses

Copyleft Licenses

• More Restrictive
• All Derivatives Free & Open
• Cannot Resell or Relicense
• Can Use Without Restriction?
  (Untested in court)
• GNU General Public License (GPL)

Proprietary License

• Commercial Software
• Define Exactly Who can Use and How
• Set Any Limits Desired

Short Version

• No License: Copyright
• Public Domain: Unlicense
• No Restrictions: MIT/BSD/Apache
• Always Free & Open: GNU GPL
• Maintain Rights: Proprietary