the.com/copyleft
copyright, but it uses its powers for good and traps freedom inside the license forever.
means a licensing trick that uses copyright law to guarantee a work and all its derivatives stay free and open, forever.
from coined by richard stallman in the 1980s as a pun on copyright, first formalized in the gnu general public license to keep software free from being locked back up by proprietary forks.
key mechanismderivative works must inherit the same license
first licensegnu gpl, released 1989
symbola backwards c, unofficial and unenforceable
nicknamecalled viral licensing by critics