Beerware is a somewhat tongue-in-cheek term for software released under a very relaxed license (beerware licensed software). It provides the end user with the right to use a particular program (or do anything else with the source code).
Should the user of the product meet the author and consider the software useful, they are encouraged to either buy the author a beer "in return" or drink one themselves. The Fedora project and Humanitarian-FOSS project at Trinity College recognized the "version 42" beerware license variant as extremely permissive "copyright only" license, and consider it as GPL compatible.As of 2016 the Free Software Foundation does not mention this license explicitly, but its list of licenses contains an entry for informal licenses, which are listed as free, non-copyleft, and GPL-compatible. However, the FSF recommends the use of more detailed licenses over informal ones.
Many variations on the beerware model have been created. Poul-Henning Kamp's beerware license is simple and short, in contrast to the GPL, which he has described as a "joke". The full text of Kamp's license is:
Last night as I lay dreaming of pleasant days gone by
Me mind being bent on rambling, to Ireland I did fly
I stepped on board a vision, and I followed with a will
'Til next I came to anchor at the cross at Spancil Hill
It being on the 23rd of June, the day before the fair
When Ireland's sons and daughters and friends assembled there
The young, the old, the brave and the bold came, their duty to fulfill
At the parish church in Clooney, a mile from Spancil Hill
I went to see me neighbors, to see what they might say
The old ones were all dead and gone, the young ones turning gray
But I met the tailor Quigley, he's as bold as ever still
Ah, he used to mend me britches when I lived in Spancil Hill
I paid a flying visit to my first and only love
She's as white as any lily, gentle as a dove
And she threw her arms around me saying, "Johnny, I love you still"
As she's Nell the farmer's daughter and the pride of Spancil Hill
I dreamed I held and kissed her as in the days of yore
Ah Johnny, you're only jokin', as many's the time before
Then the cock, he crew in the morning, he crew both loud and shrill