Z:gnu-www-ja-quick-guide-gplv3--35b198-In the 17 years since GPLv2 wa/en

In the 17 years since GPLv2 was published, the software patent landscape has changed considerably, and free software licenses have developed new strategies to address them. GPLv3 reflects these changes too. Whenever someone conveys software covered by GPLv3 that they've written or modified, they must provide every recipient with any patent licenses necessary to exercise the rights that the GPL gives them. In addition to that, if any licensee tries to use a patent suit to stop another user from exercising those rights, their license will be terminated.